Aiming at the problem of dislocation at the junction of metro carriages, a three DOF (degree of freedom) coupled vibration model of the junction of metro carriages was established. Then, the kinetic equation of vibration model was established by Lagrange method, the transfer function of the vibration model was deduced by Laplace transform, and the control system of vibration model was established by SIMULINK. In addition, the excitation signals such as the traction force, resistance force, lateral force and longitudinal force at wheel and rail were studied. Through simulation, obtain the coupling vibration characteristics under different parameters including traction force, spring stiffness and damping coefficient. The simulation results show that the amplitude differences ( the dislocation is small.