Abstract: In view of problems of large volume of transport truck, poor viewing angle of driver and easily leading to dangerous accident, the paper designed collision warning system of truck for open pit mine based on TOF technology. The system uses WSN modules with ranging capabilities, and determines locations of large vehicles, support vehicles and personnel through wireless ranging method and triangulation location method, and realizes orientation display and alarm. The test results show that ranging distance of the system is no less than 200 m, the error is no greater than 4 m, which can meet requirements of collision warning systems, meanwhile reduces system cost and power consumption.