Abstract: Most of the existing rigidity research use the quasi-static method to analyze and determine the rigidity range of track structure without considering the impact of the track rigidity on the dynamic response of the track structure. Therefore, based on the vehicle-track coupling dynamics, this paper established the vertical analysis model, andcompiled the dynamic simulation program with Matlab, analyzed the sensitivity of the dynamic response of the track structure to the change of the rigidity of the track components by using the sensitivity coefficient method, so as to obtain the reasonable rigidity of the track structure. The objective function was established by the minimum comprehensive dynamic response of the track, the optimal rigidity matching of the ballast track structure under the action of 33 t axle load freight truck was obtained as follows:fastener rigidity 120 kN/mm, ballast bed rigidity 175 kN/mm.