Abstract: In order to study the vertical coupling vibration of a low-medium speed maglev train and at-ground-structure system, a vertical coupling vibration model of the maglev train-bridge (at ground structure) system was established firstly based on the SIMPACK and ANSYS joint simulation. The joint simulation method was verified by the field experiment for a 20m simply-supported girder in a test line. Then, the vertical coupling vibration model of the maglev train and at-ground-structure system was analyzed. The influence of the parameters for the at-ground structure was discussed. The study results indicated that:the vibration frequency of the at-ground structure is relatively high; the first order vertical bending frequency is 32.9Hz; the vertical displacement and acceleration of the frame center are both bigger than that of the bottom center; the vibration of the frame is the high frequency, comparing with the bottom vibration; the acceleration is significantly greater than that of the bottom in the range of 50 Hz~100 Hz; the load frequency of the maglev train is relatively high and the loading frequency (integer multiple) is easily coincidence with or close to the natural frequency of the at-ground structure, which leads to the resonance effect and the dynamic responses of the at-ground structure are significantly enlarged; with the increase of the void length of subgrade supporting, the dynamic responses of the at-ground structure are obviously enlargement and the growth rate is increased; with the increase of uniform spring stiffness and the bottom thickness, the dynamic responses are reduced and the decrease rates are smaller.