The design of intelligent monitoring system which can be use to monitor the situation of fire and the leakage of housing is based on STC12C5608AD MCU and MQ-2 gas sensor meanwhile it includes the human body infrared module and an acousto-optic monitoring module, monitoring of the indicators by each module, and the detection result is transmitted to the micro controller. Once there is something dangerous, which can gives out the alarm, so as to some one can realize the intelligent residential burglary, fire, gas leakage prevention function so that protect residences from the loss of life and property.