The design of a multi-mode intelligent street light control system is proposed with AT89S52 micro-controller as its master chip.Three kinds of operating mode,namely road,alley or timing mode,are available for selection according to environment brightness.In the alley mode,the system detects the crossing vehicles or pedestrians by the infrared sensors,and sends the signal to the micro-controller,which will turn on the street lights.The street lights are always on in road mode to ensure the safe and quick crossing of vehicles or pedestrians.Under the timing mode,the system will turn on/off the street lights according to the timing schedule,which is set through the DS1302 timing module.Integrated with automatic fault detection,this system is intelligent and practical for street light control.