diff --git a/README.md b/README.md
index 716d26d..59d30b9 100644
--- a/README.md
+++ b/README.md
@@ -32,14 +32,27 @@ Support `MySQL`, `SQL Server` and `PostgreSQL`.
 ```js
 const rds = require('ali-rds');
 
-let db = rds({
+const db = rds({
   host: 'your-rds-address.mysql.rds.aliyuncs.com',
   port: 3306,
   user: 'your-username',
   password: 'your-password',
   database: 'your-database-name',
+
+  // optional params
+  // The charset for the connection.
+  // This is called "collation" in the SQL-level of MySQL (like utf8_general_ci).
+  // If a SQL-level charset is specified (like utf8mb4)
+  // then the default collation for that charset is used. (Default: 'UTF8_GENERAL_CI')
+  // charset: 'utf8_general_ci',
+  //
   // The maximum number of connections to create at once. (Default: 10)
   // connectionLimit: 10,
+  //
+  // The maximum number of connection requests the pool will queue
+  // before returning an error from getConnection.
+  // If set to 0, there is no limit to the number of queued connection requests. (Default: 0)
+  // queueLimit: 0,
 });
 ```
 
diff --git a/lib/client.js b/lib/client.js
index c85183f..c14f0d7 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -101,3 +101,17 @@ proto.beginTransactionScope = function* (scope, ctx) {
     throw err;
   }
 };
+
+proto.end = function(callback) {
+  // callback style
+  if (callback) return this.pool.end(callback);
+
+  // promise style
+  const that = this;
+  return new Promise(function(resolve, reject) {
+    that.pool.end(function(err) {
+      if (err) return reject(err);
+      resolve();
+    });
+  });
+};
diff --git a/package.json b/package.json
index c21aee3..47ec5a6 100644
--- a/package.json
+++ b/package.json
@@ -18,6 +18,7 @@
   },
   "devDependencies": {
     "autod": "*",
+    "co": "^4.6.0",
     "co-mocha": "*",
     "istanbul": "*",
     "jshint": "*",
@@ -41,4 +42,4 @@
   },
   "author": "fengmk2 <m@fengmk2.com> (http://fengmk2.com)",
   "license": "MIT"
-}
+}
\ No newline at end of file
diff --git a/test/client.test.js b/test/client.test.js
index f1f8df3..0e1b513 100644
--- a/test/client.test.js
+++ b/test/client.test.js
@@ -4,6 +4,7 @@
  * Module dependencies.
  */
 
+const co = require('co');
 const assert = require('assert');
 const rds = require('../');
 const config = require('./config');
@@ -16,6 +17,10 @@ describe('client.test.js', function () {
     yield this.db.query('delete from ?? where name like ?', [table, prefix + '%']);
   });
 
+  after(function(done) {
+    this.db.end(done);
+  });
+
   describe('rds(options)', function () {
     it('should connect rds success', function* () {
       let rows = yield this.db.query('show tables');
@@ -820,4 +825,31 @@ describe('client.test.js', function () {
       assert.equal(count, 0);
     });
   });
+
+  describe('mock query after client end', function() {
+    it('should query throw error after end', function*() {
+      const db = rds(config);
+      yield db.query('select * from ?? limit 10', [table]);
+      yield db.end();
+      const db2 = rds(config);
+
+      try {
+        yield db.query('select * from ?? limit 10', [table]);
+        throw new Error('should not run this');
+      } catch (err) {
+        assert.equal(err.message, 'Pool is closed.');
+      }
+
+      yield db2.query('select * from ?? limit 10', [table]);
+      yield db2.end();
+    });
+
+    it('should support end with callback style', function(done) {
+      const db = rds(config);
+      co(function*() {
+        yield db.query('select * from ?? limit 10', [table]);
+        db.end(done);
+      }).catch(done);
+    });
+  });
 });