Abstract: In this paper,based on the movel I/O expansion chip called GM 8166,an intelligent fire prevention and security system is designed which takes AT89C51 as a core.when something unexpected happens,it can automatically and promptly set up the corresponding equipment,raise the alarm,show the information and by using the MODBUS protocol,correspond with the fire security center.

Key words: fire prevention and security； GM8166； MAX7219:HN911； MODBUS；