It is usually need to supervise and control gathering data and working status of PLC in industry control.There are some ways such as VB,DELPHI,PB to carry out the requirement.Visual C++ is an exploiture tool for Windows application program and has quite strong function in the aspect of image processing and database managing etc.It has faster speed to realize bottom communication control.Using Visual C++ and MFC,the authors implement the serial communication system between PC and PLC.The paper introduces the communication protocol and software design method and realizes data's sending and incepted rapidly,real-time auto-control accurately and quickly.This system is simple,economical,and reliable and has an application value,which has been applied successfully in real system.