The motor of linear motor vehicle is in the elastic suspension system, which bears the impact of wheelset and electromagnetic force. Based on a linear motor vehicle, a multi-rigid-body dynamic model was established. Considering the electromagnetic force of the motor, Simpack and Simulink were used to simulate the effect of different vertical stiffness of the suspension device from the aspects of air gap of the linear motor, vehicle dynamic performance and motor vibration. The results show that the vertical stiffness of the suspension device of linear motor has an effect on the safety of vehicle curve passing and running smoothness. Increasing the vertical stiffness can reduce the vertical force of wheel and rail and the vertical smoothness index, while the lateral smoothness index will slightly increase. The air gap changes greatly when the vertical stiffness is small, and increasing the vertical stiffness can reduce the air gap change and the motor vibration, however, large vertical stiffness will increase the high-frequency vibration components of the motor. Considering comprehensively, it is suggested that the vertical stiffness of the support joints of the motor suspension beam in the motor suspension device should range from 24 MN/m to 60 MN/m and the vertical stiffness of derrick joints should range from 192 MN/m to 480 MN/m.