With the development of highway transportation and automobile industry technology, highway truck overload phenomenon occurs frequently, which poses a danger to road safety and personnel life safety. So it is very important to identify the overload phenomenon. Traditionally, static detection is adopted for overload identification, which has low efficiency. Aiming at this phenomenon, a dynamic overload identification method is proposed. Firstly, the coupled road excitation model of vehicle speed and speed bump is established, and then the 4-DOF vehicle model of half car is established. At the same time, considering that the double input vibration of the front and rear wheels will be coupled when vehicle passes through the speed bump, the model is decoupled. Then, the vertical trajectory of the body in the front axle position is obtained by Carsim software simulation. According to the established vehicle dynamic model, the body mass is inversely estimated and compared with the rated load to determine whether it is overloaded. The estimated mass is brought into the half-car model built by simulink to obtain the centroid vibration acceleration, which is compared with the Carsim model. The reliability of the method is verified. The results show that this method can realize the identification and detection of overload of heavy vehicles, and improve the recognition accuracy. The average error is 7.3%, which promotes the further research of overload identification.