Establish a three-dimensional finite element ballastless track-subgrade-natural foundation soil nonlinear numerical analysis model, calculate the wheel-rail load based on the random irregularity of the track, and import the wheel-rail load into the finite element model through the secondary development subroutine of the finite element software. The finite element element is used inside the model. The infinite element elements are used to simulate the actual semi-infinite space of the project at both ends of the subgrade and around the natural foundation soil. The Drucker-Prager elastoplastic constitutive model is used for the subgrade and natural foundation soil. Law of dynamic stress distribution of subgrade under moving load. The research results show that the vertical dynamic stress is distributed along the lateral direction, and the value in the track structure is larger, the subgrade bed is much smaller than the value in the track structure, and the “saddle” distribution appears on the surface of the bed and the bottom of the bed; along the vertical As the depth increases, the vertical dynamic stress gradually decreases, and the attenuation rate in the surface layer of the bed is large, even more than 50%; along the longitudinal distribution, the number of train wheel pairs is generated in the track structure layer. The number of stress peaks in the subgrade bed is reduced due to the superposition of the dynamic responses generated by the wheelsets close to each other, and the number of stress peaks is reduced; the subgrade bed plays a major role in dispersing and buffering the vertical dynamic stress, and the concrete The contact part between the edge of the base and the surface layer of the bed is prone to damage, so it should be given enough attention in the design.