The joint simulation method of Abaqus and Fortran to build the three -dimensional finite element analysis model of maglev train-track beam-subgrade-foundation coupling system based on the artificial boundaries condition for infinite element. The effects of different driving speed, subgrade stiffness and damping of subgrade bed on dynamic stress distribution and transmission law of low subgrade for medium and low speed maglev under medium speed driving are studied. The results show that the subgrade dynamic stress increases with the increase of running speed, and has little effect on the subgrade below 0.6 m; Under the condition of different subgrade bed stiffness, the greater the stiffness of subgrade bed, the greater the dynamic stress on the surface of subgrade, but the increasing amplitude is gradually slowing down, the dynamic stress of subgrade decreases with the increase of subgrade stiffness when the subgrade below 0.6 m; Different subgrade damping has no effect on the dynamic stress of the surface of subgrade, but it has a great influence on the dynamic stress at different depths under the subgrade, the larger the subgrade damping is, the smaller the dynamic stress of subgrade is, the greater the attenuation amplitude of dynamic stress is.