diff --git a/History.md b/History.md
index 3bd193e..55526e1 100644
--- a/History.md
+++ b/History.md
@@ -1,6 +1,7 @@
 2.1.1 / 2018-03-06
 ==================
   * Bug修复
+  * 修改连接方式
   * 异常返回的格式改为对象
 
 
diff --git a/index.js b/index.js
index c308928..fe27909 100644
--- a/index.js
+++ b/index.js
@@ -59,25 +59,8 @@ class Mysqli {
   }
 
   emit(fromSlave = false, db) {
-    const defer = Promise.defer()
     const slave = fromSlave && this.useSlaveDB ? 'SLAVE*' : 'MASTER'
-
-    this.pool.getConnection(slave, (err, conn) => {
-      if (err) {
-        return defer.reject({ err: `MySQL connect ${err}`, sql: '' })
-      }
-      if (db) {
-        conn.query('USE ' + db, err => {
-          if (err) {
-            return defer.reject({ err: 'Select DB ' + err, sql: '' })
-          }
-          defer.resolve(conn)
-        })
-      } else {
-        defer.resolve(conn)
-      }
-    })
-    return new Method(defer.promise)
+    return new Method(this.pool, slave, db)
   }
 }
 
diff --git a/lib/method.js b/lib/method.js
index f1bdc27..f929098 100644
--- a/lib/method.js
+++ b/lib/method.js
@@ -9,15 +9,38 @@ const { escape } = require('mysql')
 const parser = require('./parser')
 
 class Method {
-  constructor(defer) {
-    this.defer = defer
+  constructor(pool, slave, db) {
+    this.pool = pool
+    this.slave = slave
+    this.db = db
+  }
+
+  connect() {
+    this.defer = Promise.defer()
+    this.pool.getConnection(this.slave, (err, conn) => {
+      if (err) {
+        return this.defer.reject({ err: `MySQL connect ${err}`, sql: '' })
+      }
+      if (this.db) {
+        conn.query('USE ' + this.db, err => {
+          if (err) {
+            return this.defer.reject({ err: 'Select DB ' + err, sql: '' })
+          }
+          this.defer.resolve(conn)
+        })
+      } else {
+        this.defer.resolve(conn)
+      }
+    })
+    return this.defer.promise
   }
 
   listDb() {
-    return this.defer.then(conn => {
+    return this.connect().then(conn => {
       const defer = Promise.defer()
 
       conn.query('SHOW DATABASES', (err, row) => {
+        conn.release()
         if (err) {
           return defer.reject({
             err: 'SHOW DATABASES ' + err,
@@ -33,10 +56,11 @@ class Method {
 
   //返回数据表
   listTable() {
-    return this.defer.then(conn => {
+    return this.connect().then(conn => {
       const defer = Promise.defer()
 
       conn.query('SHOW TABLES', (err, row) => {
+        conn.release()
         if (err) {
           return defer.reject({
             err: 'SHOW TABLES ' + err,
@@ -55,18 +79,20 @@ class Method {
    * @param  {[type]}   sql       [sql语句]
    */
   query(sql) {
-    if (typeof sql !== 'string')
+    if (typeof sql !== 'string') {
       return Promise.reject({
         err: `Query error, argument sql must be string. ${typeof sql} given`,
-        sql
+        sql: sql
       })
+    }
 
-    return this.defer.then(conn => {
+    return this.connect().then(conn => {
       const defer = Promise.defer()
 
       conn.query(sql, (err, result) => {
+        conn.release()
         if (err) {
-          return defer.reject({ err: `Query ${err}`, sql })
+          return defer.reject({ err: `Query ${err}`, sql: sql })
         }
         defer.resolve(result)
       })
@@ -78,7 +104,7 @@ class Method {
     const { table, leftJoin, rightJoin, join, where, sort, limit } = condition
     let sql = ''
     if (!table) {
-      return Promise.reject({ err: 'Find Error: empty table', sql })
+      return Promise.reject({ err: 'Find Error: empty table', sql: sql })
     }
 
     sql = parser.select(select)
@@ -105,12 +131,13 @@ class Method {
       sql += parser.limit(limit)
     }
 
-    return this.defer.then(conn => {
+    return this.connect().then(conn => {
       const defer = Promise.defer()
 
       conn.query(sql, (err, result) => {
+        conn.release()
         if (err) {
-          return defer.reject({ err: `Find ${err}`, sql })
+          return defer.reject({ err: `Find ${err}`, sql: sql })
         }
         defer.resolve(result)
       })
@@ -135,7 +162,7 @@ class Method {
   insert({ table }, doc) {
     let sql = ''
     if (!table) {
-      return Promise.reject({ err: 'Insert Error: empty table', sql })
+      return Promise.reject({ err: 'Insert Error: empty table', sql: sql })
     }
 
     sql = `INSERT INTO ${table} `
@@ -148,12 +175,13 @@ class Method {
     }
     sql += `(${keys.join(',')}) VALUES (${vals.join(',')})`
 
-    return this.defer.then(conn => {
+    return this.connect().then(conn => {
       const defer = Promise.defer()
 
       conn.query(sql, (err, result) => {
+        conn.release()
         if (err) {
-          return defer.reject({ err: `Insert ${err}`, sql })
+          return defer.reject({ err: `Insert ${err}`, sql: sql })
         }
 
         defer.resolve(result.insertId)
@@ -166,7 +194,7 @@ class Method {
   update({ table, where }, doc) {
     let sql = ''
     if (!table) {
-      return Promise.reject({ err: 'Update Error: empty table', sql })
+      return Promise.reject({ err: 'Update Error: empty table', sql: sql })
     }
 
     sql = `UPDATE ${table} SET `
@@ -184,11 +212,12 @@ class Method {
     sql += fields.join(',')
     sql += parser.where(where)
 
-    return this.defer.then(conn => {
+    return this.connect().then(conn => {
       const defer = Promise.defer()
       conn.query(sql, (err, res) => {
+        conn.release()
         if (err) {
-          return defer.reject({ err: `Update ${err}`, sql })
+          return defer.reject({ err: `Update ${err}`, sql: sql })
         }
 
         defer.resolve(res.affectedRows)
@@ -200,7 +229,7 @@ class Method {
   remove({ table, where }) {
     let sql = ''
     if (!table) {
-      return Promise.reject({ err: 'Remove Error: empty table', sql })
+      return Promise.reject({ err: 'Remove Error: empty table', sql: sql })
     }
 
     sql = `DELETE FROM \`${table}\` `
@@ -209,11 +238,12 @@ class Method {
       sql += parser.where(where)
     }
 
-    return this.defer.then(conn => {
+    return this.connect().then(conn => {
       const defer = Promise.defer()
       conn.query(sql, (err, res) => {
+        conn.release()
         if (err) {
-          return defer.reject({ err: `Remove ${err}`, sql })
+          return defer.reject({ err: `Remove ${err}`, sql: sql })
         }
 
         defer.resolve(res.affectedRows)
diff --git a/package.json b/package.json
index ca97f7a..34f2fbb 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mysqli",
-  "version": "2.1.1",
+  "version": "2.1.2",
   "description": "MySQL tool",
   "main": "index.js",
   "dependencies": {