Abstract: This paper takes the Datong-Xi'an passenger transport line subgrade orthogonally crossing ground fissure zone as research object. It establishes the foundation-ground fissure-embankment dynamic calculation model of high-speed railway with the finite element numerical method. It simulates and analyzes the dynamic response characteristics of subgrade on natural foundation with and without ground fissure zone under the action of high-speed train load. The results show that the response of dynamic displacement, acceleration and dynamic stratum stress of subgrade in natural site without ground fissure under train load is basically steady without obvious differences. In ground fissure site, the dynamic displacement of subgrade and the acceleration of embankment body both increases in the hanging wall and decreases in the footwall of active ground fissure zone, and the attenuation amplitude of dynamic displacement and acceleration of the subgrade in the footwall is greater than that of the hanging wall of ground fissure zone in perpendicular direction of train line. The critical influence depth of acceleration induced by ground fissure is about 15m below the ground. The dynamic stress in subgrade reduces in the hanging wall and increases in the footwall of ground fissure. The dynamic stress critical depth of subgrade in ground fissure site is 10m below the ground. The research results can provide scientific basis for the construction of high-speed railway and disaster prevention and mitigation in ground fissure development area in China.