diff --git a/conf/config.yaml b/conf/config.yaml
index c860d9347b12..9864584a2dc4 100644
--- a/conf/config.yaml
+++ b/conf/config.yaml
@@ -3,6 +3,7 @@ apisix:
   node_ssl_listen: 9443
   enable_heartbeat: true
   enable_admin: true
+  enable_debug: false
   allow_admin: "127.0.0.0/24"
   real_ip_header: "X-Real-IP"     # http://nginx.org/en/docs/http/ngx_http_realip_module.html#real_ip_header
   real_ip_from:                   # http://nginx.org/en/docs/http/ngx_http_realip_module.html#set_real_ip_from
diff --git a/doc/architecture-design-cn.md b/doc/architecture-design-cn.md
index 5c05492d2648..c4b8e8a93ece 100644
--- a/doc/architecture-design-cn.md
+++ b/doc/architecture-design-cn.md
@@ -6,6 +6,7 @@
 - [**Consumer**](#consumer)
 - [**Plugin**](#plugin)
 - [**Upstream**](#upstream)
+- [**Debug mode**](#Debug-mode)
 
 ## apisix
 
@@ -322,3 +323,28 @@ curl http://127.0.0.1:9080/apisix/admin/routes/1 -X PUT -d '
 更多细节可以参考[健康检查的文档](health-check.md).
 
 [返回目录](#目录)
+
+
+## Debug mode
+
+开启调试模式后，会在请求应答时，输出更多的内部信息，比如加载了哪些插件等。
+
+设置 `conf/config.yaml` 中的 `apisix.enable_debug` 为 `true`，即可开启调试模式。
+
+比如对 `/hello` 开启了 `limit-conn`和`limit-count`插件，这时候应答头中会有 `Apisix-Plugins: limit-conn, limit-count` 出现。
+
+```shell
+$ curl http://127.0.0.1:1984/hello -i
+HTTP/1.1 200 OK
+Content-Type: text/plain
+Transfer-Encoding: chunked
+Connection: keep-alive
+Apisix-Plugins: limit-conn, limit-count
+X-RateLimit-Limit: 2
+X-RateLimit-Remaining: 1
+Server: openresty
+
+hello world
+```
+
+[返回目录](#目录)
diff --git a/lua/apisix/core/config_etcd.lua b/lua/apisix/core/config_etcd.lua
index 4cb8856b1abc..51ded460cba6 100644
--- a/lua/apisix/core/config_etcd.lua
+++ b/lua/apisix/core/config_etcd.lua
@@ -1,6 +1,6 @@
 -- Copyright (C) Yuansheng Wang
 
-local fetch_local_conf = require("apisix.core.config_local").local_conf
+local config_local = require("apisix.core.config_local")
 local log          = require("apisix.core.log")
 local json         = require("apisix.core.json")
 local etcd         = require("resty.etcd")
@@ -22,9 +22,11 @@ local pcall        = pcall
 
 
 local _M = {
-    version = 0.1,
-    local_conf = fetch_local_conf,
+    version = 0.2,
+    local_conf = config_local.local_conf,
+    clear_local_cache = config_local.clear_cache,
 }
+
 local mt = {
     __index = _M,
     __tostring = function(self)
@@ -300,7 +302,7 @@ end
 
 
 function _M.new(key, opts)
-    local local_conf, err = fetch_local_conf()
+    local local_conf, err = config_local.local_conf()
     if not local_conf then
         return nil, err
     end
diff --git a/lua/apisix/core/config_local.lua b/lua/apisix/core/config_local.lua
index 265201129e1f..fe3d434f43e9 100644
--- a/lua/apisix/core/config_local.lua
+++ b/lua/apisix/core/config_local.lua
@@ -6,9 +6,12 @@ local ngx = ngx
 local io_open = io.open
 local type = type
 local local_conf_path = ngx.config.prefix() .. "conf/config.yaml"
+local config_data
 
 
-local _M = {version = 0.1}
+local _M = {
+    version = 0.2,
+}
 
 
 local function read_file(path)
@@ -23,14 +26,23 @@ local function read_file(path)
     return content
 end
 
+function _M.clear_cache()
+    config_data = nil
+end
+
+
+function _M.local_conf(force)
+    if not force and config_data then
+        return config_data
+    end
 
-function _M.local_conf()
     local yaml_config, err = read_file(local_conf_path)
     if type(yaml_config) ~= "string" then
         return nil, "failed to read config file:" .. err
     end
 
-    return yaml.parse(yaml_config)
+    config_data = yaml.parse(yaml_config)
+    return config_data
 end
 
 
diff --git a/lua/apisix/plugin.lua b/lua/apisix/plugin.lua
index de62b695532d..7b3ddc63d404 100644
--- a/lua/apisix/plugin.lua
+++ b/lua/apisix/plugin.lua
@@ -8,10 +8,11 @@ local pairs = pairs
 local type = type
 local local_plugins = core.table.new(10, 0)
 local local_plugins_hash = core.table.new(10, 0)
+local local_conf
 
 
 local _M = {
-    version = 0.1,
+    version = 0.2,
     load_times = 0,
     plugins = local_plugins,
     plugins_hash = local_plugins_hash,
@@ -19,7 +20,7 @@ local _M = {
 
 
 local function sort_plugin(l, r)
-    return l.priority >= r.priority
+    return l.priority > r.priority
 end
 
 
@@ -59,7 +60,7 @@ local function load()
     core.table.clear(local_plugins)
     core.table.clear(local_plugins_hash)
 
-    local local_conf = core.config.local_conf()
+    local_conf = core.config.local_conf(true)
     local plugin_names = local_conf.plugins
     if not plugin_names then
         return nil, "failed to read plugin list form local file"
@@ -82,8 +83,14 @@ local function load()
         sort_tab(local_plugins, sort_plugin)
     end
 
-    for _, plugin in ipairs(local_plugins) do
+    for i, plugin in ipairs(local_plugins) do
         local_plugins_hash[plugin.name] = plugin
+        if local_conf and local_conf.apisix
+           and local_conf.apisix.enable_debug then
+            core.log.warn("loaded plugin and sort by priority:",
+                          " ", plugin.priority,
+                          " name: ", plugin.name)
+        end
     end
 
     _M.load_times = _M.load_times + 1
@@ -136,6 +143,9 @@ function _M.filter(user_route, plugins)
     plugins = plugins or core.table.new(#local_plugins * 2, 0)
     local user_plugin_conf = user_route.value.plugins
     if user_plugin_conf == nil then
+        if local_conf and local_conf.apisix.enable_debug then
+            core.response.set_header("Apisix-Plugins", "no plugin")
+        end
         return plugins
     end
 
@@ -149,6 +159,14 @@ function _M.filter(user_route, plugins)
         end
     end
 
+    if local_conf.apisix.enable_debug then
+        local t = {}
+        for i = 1, #plugins, 2 do
+            core.table.insert(t, plugins[i].name)
+        end
+        core.response.set_header("Apisix-Plugins", core.table.concat(t, ", "))
+    end
+
     return plugins
 end
 
diff --git a/lua/apisix/plugins/example-plugin.lua b/lua/apisix/plugins/example-plugin.lua
index e8ae9eca1193..75871bbe0d9a 100644
--- a/lua/apisix/plugins/example-plugin.lua
+++ b/lua/apisix/plugins/example-plugin.lua
@@ -21,7 +21,7 @@ local plugin_name = "example-plugin"
 
 local _M = {
     version = 0.1,
-    priority = 1000,        -- TODO: add a type field, may be a good idea
+    priority = 0,        -- TODO: add a type field, may be a good idea
     name = plugin_name,
     schema = schema,
 }
diff --git a/lua/apisix/plugins/heartbeat.lua b/lua/apisix/plugins/heartbeat.lua
index 370b8e0de045..7e1fdf84213e 100644
--- a/lua/apisix/plugins/heartbeat.lua
+++ b/lua/apisix/plugins/heartbeat.lua
@@ -11,7 +11,7 @@ local apisix_heartbeat_addr = "https://iresty.com/apisix/heartbeat?"
 
 local _M = {
     version = 0.1,
-    priority = 1000,
+    priority = 100,
     name = plugin_name,
 }
 
diff --git a/t/debug-mode.t b/t/debug-mode.t
new file mode 100644
index 000000000000..3f56ff63a897
--- /dev/null
+++ b/t/debug-mode.t
@@ -0,0 +1,159 @@
+use t::APISix 'no_plan';
+
+repeat_each(1);
+no_long_string();
+no_root_location();
+
+sub read_file($) {
+    my $infile = shift;
+    open my $in, $infile
+        or die "cannot open $infile for reading: $!";
+    my $cert = do { local $/; <$in> };
+    close $in;
+    $cert;
+}
+
+our $yaml_config = read_file("conf/config.yaml");
+$yaml_config =~ s/node_listen: 9080/node_listen: 1984/;
+$yaml_config =~ s/enable_heartbeat: true/enable_heartbeat: false/;
+$yaml_config =~ s/enable_debug: false/enable_debug: true/;
+
+
+run_tests;
+
+__DATA__
+
+=== TEST 1: loaded plugin
+--- config
+    location /t {
+        content_by_lua_block {
+            ngx.sleep(0.3)
+            ngx.say("done")
+        }
+    }
+--- yaml_config eval: $::yaml_config
+--- request
+GET /t
+--- response_body
+done
+--- grep_error_log eval
+qr/loaded plugin and sort by priority: [-\d]+ name: [\w-]+/
+--- grep_error_log_out
+loaded plugin and sort by priority: 2510 name: jwt-auth
+loaded plugin and sort by priority: 2500 name: key-auth
+loaded plugin and sort by priority: 1003 name: limit-conn
+loaded plugin and sort by priority: 1002 name: limit-count
+loaded plugin and sort by priority: 1001 name: limit-req
+loaded plugin and sort by priority: 1000 name: node-status
+loaded plugin and sort by priority: 500 name: prometheus
+loaded plugin and sort by priority: 0 name: example-plugin
+loaded plugin and sort by priority: -1000 name: zipkin
+
+
+
+=== TEST 2: set route(no plugin)
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/routes/1',
+                 ngx.HTTP_PUT,
+                 [[{
+                        "methods": ["GET"],
+                        "uri": "/hello",
+                        "upstream": {
+                            "nodes": {
+                                "127.0.0.1:1980": 1
+                            },
+                            "type": "roundrobin"
+                        }
+                }]]
+                )
+
+            if code >= 300 then
+                ngx.status = code
+            end
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+--- no_error_log
+[error]
+
+
+
+=== TEST 3: hit routes
+--- request
+GET /hello
+--- yaml_config eval: $::yaml_config
+--- response_body
+hello world
+--- response_headers
+Apisix-Plugins: no plugin
+--- no_error_log
+[error]
+
+
+
+=== TEST 4: set route(one plugin)
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/routes/1',
+                 ngx.HTTP_PUT,
+                 [[{
+                        "methods": ["GET"],
+                        "plugins": {
+                            "limit-count": {
+                                "count": 2,
+                                "time_window": 60,
+                                "rejected_code": 503,
+                                "key": "remote_addr"
+                            },
+                            "limit-conn": {
+                                "conn": 100,
+                                "burst": 50,
+                                "default_conn_delay": 0.1,
+                                "rejected_code": 503,
+                                "key": "remote_addr"
+                            }
+                        },
+                        "upstream": {
+                            "nodes": {
+                                "127.0.0.1:1980": 1
+                            },
+                            "type": "roundrobin"
+                        },
+                        "uri": "/hello"
+                }]]
+                )
+
+            if code >= 300 then
+                ngx.status = code
+            end
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+--- no_error_log
+[error]
+
+
+
+=== TEST 5: hit routes
+--- request
+GET /hello
+--- yaml_config eval: $::yaml_config
+--- response_body
+hello world
+--- response_headers
+Apisix-Plugins: limit-conn, limit-count
+--- no_error_log
+[error]
diff --git a/t/plugin/example.t b/t/plugin/example.t
index da35174b5d85..69cff74f13e3 100644
--- a/t/plugin/example.t
+++ b/t/plugin/example.t
@@ -145,7 +145,7 @@ done
 --- request
 GET /t
 --- response_body
-plugin name: example-plugin priority: 1000
+plugin name: example-plugin priority: 0
 --- yaml_config
 etcd:
   host: "http://127.0.0.1:2379" # etcd address