diff --git a/COPYRIGHT b/COPYRIGHT
index e31ac1f812a61..ad8a171d9dd28 100644
--- a/COPYRIGHT
+++ b/COPYRIGHT
@@ -239,6 +239,8 @@ Redistributions in binary form must reproduce the above copyright notice, this l
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+%%%%%%%%%
+
 opentracing-openresty
 
 https://github.com/iresty/opentracing-openresty
diff --git a/doc/plugins/zipkin.md b/doc/plugins/zipkin.md
new file mode 100644
index 0000000000000..bcfd4d730b49d
--- /dev/null
+++ b/doc/plugins/zipkin.md
@@ -0,0 +1,92 @@
+# Summary
+- [**Name**](#name)
+- [**Attributes**](#attributes)
+- [**How To Enable**](#how-to-enable)
+- [**Test Plugin**](#test-plugin)
+- [**Disable Plugin**](#disable-plugin)
+
+
+## Name
+
+`Zipkin` is a OpenTracing plugin.
+
+It's also works with `Apache SkyWalking`, which is support Zipkin v1/v2 format.
+
+## Attributes
+
+* `endpoint`: the http endpoint of Ziplin, for example: `http://127.0.0.1:9411/api/v2/spans`.
+
+* `sample_ratio`: the ratio of sample, the default value is 0.001, the minimum is 0.00001, the maximum is 1.
+
+## How To Enable
+
+Here's an example, enable the zipkin plugin on the specified route:
+
+```shell
+curl http://127.0.0.1:9080/apisix/admin/routes/1 -X PUT -d '
+{
+	"methods": ["GET"],
+	"uri": "/index.html",
+	"plugins": {
+		"zipkin": {
+			"endpoint": "http://127.0.0.1:9411/api/v2/spans",
+			"sample_ratio": 1
+		}
+	},
+	"upstream": {
+		"type": "roundrobin",
+		"nodes": {
+			"39.97.63.215:80": 1
+		}
+	}
+}'
+```
+
+## Test Plugin
+
+### run the Zipkin instance
+
+e.g. using docker:
+
+```
+sudo docker run -d -p 9411:9411 openzipkin/zipkin
+```
+
+Here is a test example:
+
+```shell
+$ curl http://127.0.0.1:9080/index.html
+HTTP/1.1 200 OK
+...
+```
+
+Then you can use a browser to access the webUI of Zipkin:
+
+```
+http://127.0.0.1:9411/zipkin
+```
+
+## Disable Plugin
+
+When you want to disable the zipkin plugin, it is very simple,
+ you can delete the corresponding json configuration in the plugin configuration,
+  no need to restart the service, it will take effect immediately:
+
+```shell
+$ curl http://127.0.0.1:2379/v2/keys/apisix/routes/1 -X PUT -d value='
+{
+	"methods": ["GET"],
+	"uri": "/index.html",
+	"id": 1,
+	"plugins": {
+	},
+	"upstream": {
+		"type": "roundrobin",
+		"nodes": {
+			"39.97.63.215:80": 1
+		}
+	}
+}'
+```
+
+The zipkin plugin has been disabled now. It works for other plugins.
diff --git a/lua/apisix/core/request.lua b/lua/apisix/core/request.lua
index 0071bda607cf7..9ca6c541ab2bc 100644
--- a/lua/apisix/core/request.lua
+++ b/lua/apisix/core/request.lua
@@ -2,7 +2,7 @@
 
 local ngx = ngx
 local get_headers = ngx.req.get_headers
-
+local tonumber = tonumber
 
 local _M = {version = 0.1}
 
diff --git a/lua/apisix/core/response.lua b/lua/apisix/core/response.lua
index 2e23096c9649c..d17f385af78fe 100644
--- a/lua/apisix/core/response.lua
+++ b/lua/apisix/core/response.lua
@@ -11,6 +11,7 @@ local ngx_exit = ngx.exit
 local insert_tab = table.insert
 local concat_tab = table.concat
 local str_sub = string.sub
+local tonumber = tonumber
 
 local _M = {version = 0.1}
 
diff --git a/lua/apisix/plugins/zipkin.lua b/lua/apisix/plugins/zipkin.lua
index 5b405334493ac..534da6126418d 100644
--- a/lua/apisix/plugins/zipkin.lua
+++ b/lua/apisix/plugins/zipkin.lua
@@ -3,6 +3,8 @@ local new_tracer = require("opentracing.tracer").new
 local zipkin_codec = require("apisix.plugins.zipkin.codec")
 local new_random_sampler = require("apisix.plugins.zipkin.random_sampler").new
 local new_reporter = require("apisix.plugins.zipkin.reporter").new
+local ngx = ngx
+local pairs = pairs
 
 local plugin_name = "zipkin"
 
diff --git a/t/admin/plugins.t b/t/admin/plugins.t
index 158bba6ddb9f7..68ac848d3a576 100644
--- a/t/admin/plugins.t
+++ b/t/admin/plugins.t
@@ -14,6 +14,6 @@ __DATA__
 --- request
 GET /apisix/admin/plugins/list
 --- response_body_like eval
-qr/example-plugin","limit-req","limit-count","key-auth","prometheus","limit-conn","node-status"/
+qr/\["example-plugin","limit-req","limit-count","limit-conn","key-auth","prometheus","node-status","jwt-auth","zipkin"\]/
 --- no_error_log
 [error]