With the diversity of social and economic development, buildings, structures, Applied Materials, the development of various industrial and science and technology, increase in combustible materials, coupled with people's living environment and lifestyle changes, the risk of fire is increasing, the number of firescasualties and economic losses caused by fire is gradually increasing. Fire as the enemy of endangering the survival of mankind, more attention has been paid. With the growing number of high-rise buildings, fire hazards increase. Event of fire, will people's lives and property caused great harm, so people began to seek a method of early detection of fire, in order to control and extinguish fires and to minimize losses, protect life the development of electronic science and technology, electronics technology has become a powerful means of security, many security aspects of electronic products, the right-hand man of the people's lives. This design uses a microcontroller technology with A / D conversion chip to build a combustible gas detector alarm. When the leak of flammable or toxic gases in the environment to the critical point of the combustible gas concentration reaches the alarm set, when the gas alarm detection, combustible gas alarm will send alarm signal to remind staff to take safety measures. This paper briefly describes the design combustible gas detection alarm as well as the advantages of the SCM system; then details the design flow of the combustible gas detection alarm, as well as hardware and software systems design and software programming detailed steps, including the various modules of the program design and system debugging and simulation steps, design uses the MQ-2 gas sensor signal acquisition tool as a combustible gas, the collected analog voltage after the ADC0809 converted into digital signals. Single-chip digital signal acquisition to the ADC0809 has been calculated, if the combustible gas concentration reaches the critical point when the alarm is set microcontroller will drive the LED and buzzer alarm signal. In the case of non-combustible gases, the occurrence of unknown danger, the alarm can artificially control buttons to change the fire alarm initial value. 希望能帮到你