Abstract: The traffic signal simulation system was designed by the chip P89V51RD2、74LS595、MAX232.The system software was implemented by using of Visual Basic 6.0, and KeilC. KeilC was used in microcontroller programming for the lower computer control; The serial communication programming in VB 6.0 was used in communications with the lower computer. A communication protocol is proposed for the communications between the upper and lower computers to improve reliability. The system can dynamically control 217 LED lights with the functions of saving, reading, displaying, and clearing the signals. The effectiveness of the system was demonstrated by experiments.