Abstract: The interaction between track structure and subgrade under dynamic trains, a typical issue of soil-structure interaction, threatens the safety of high-speed trains and long-term durability of subgrade. Dynamic experimental equipment for subgrade of high-speed railways is introduced, which can be used to carry out tests on the interaction of track structure-subgrade system and long-term deformation of subgrade and foundation. The load transfer law of trains is proposed based on the load distribution tests on fastening systems. Compared with the theoretical results, a simplified formula for load distribution is given for mechanical analysis of subgrade. Meanwhile, the relationship between dynamic response of track structure and subgrade and loading frequency is summarized, and the resonance mechanism is discussed using the concentrated mass model. The results show that the first-order natural frequency of the system is 16 Hz approximately. Finally, the relationship between attenuation law of dynamic stress of subgrade at different depths and loading frequency is put forward through dynamic loading tests. As a powerful and comprehensive test equipment, it would provide an important support for future researches on geotechnical engineering problems of subgrades of high-speed railways.