In some cases necessary to weigh vehicles,an electromechanical weighing system has been developed,which consists of automobile leaf springs,capacitance sensors together with measuring circuits and other major components.To increase the modeling accuracy,it is necessary to consider not only mechanical freedom,but also the electrical freedom.In this paper,the dynamic model based on the Lagrange-Maxwell equation is presented.Simulation results and test data show that the modeling is feasible and effective.One feature of the system is that it can provide static and dynamic measurements.