Aiming at the present situation of truck overloading in transport on domestic road, a realtime monitoring system for transmission shaft torque was designed, and a test platform was built. The relationships between truck output shaft torque and the truck load during the process of starting were investigated on 2 different roads, cement road, dry sand road, respectively. Some experimental results were obtained. The starting torque and the load have a linear relationship between them. This test system can detect truck load by monitoring the output torque of the transmission shaft. The results provide certain reference for solving the problem of truck overloading testing and controlling.