The AC servo positioning control technique of micro-machining center is introduced. The system composing of the micro-machining center,Y axis servo position control interface,servo driver parameters settings and servo driving control method are discussed.The manual control,automatic home return control and positioning control are analyzed in detail,the application results show that the AC servo position control system have the advantage of simple control method,steady operation,fast response and highly accurate positioning,and it meets the demand of positioning controls of the micro-machining center.