Serial communication plays an essential role in data acquisition system. It is convenient and efficient to realize serial data communication by using communication control of VB\{6.0\}, comparing with other programming methods. Serial data communication system for LED displaying between PC and multi-microcomputer is designed through the collaboration of parity-bit of 8250 and SM\-2 of 8031. The flow chart and some programming skill based on VB6.0 are introduced in detail. The confliction between communication mode 0 and mode 1 is solved when they are used simultaneously. The experimental result shows that easy and practical design can increase the efficiency of system design.