During the bad weather， streetlights based on sunrise/sunset times control can’t be switched on earlier and postponed off. A solution is presented. The light sensors are installed at each streetlight transformer station. Remote terminal unit（RTU） detects light level， and sends alarm message to control center when it gets lower in lighting on or higher in lighting off than threshold. As received a alarm message from RTU， the system selects a rectangle region by the reference of alarmed RTU locations on geographical map and enlarges region by exponential growth. The system queries all RTUs in the selected region， switches on/off streetlights by the rate of alarmed RTUs number in all queried RTUs. This control approach can identify abnormal alarms of RTU， control streetlights on/off in partial region， reduce electrical consumption of streetlights.