Abstract: Railway subgrade is one of the important components of train operation. In the past study of train dynamic load，the height of subgrade is generally less than 15 m，and the dynamic response law of subgrade up to 20 m has not been explored. Based on the Yungui railway project，FLAC3D numerical simu⁃ lation is carried out to explore the dynamic response characteristics of train loads. The results show that un⁃ der the action of train load，the dynamic stress is consistent with the change trend of plastic deformation， and gradually decreases from the surface of the foundation bed. The effective influence depth of train load is within 8.8 m. With the increase of the number of dynamic load cycles，the total settlement of subgrade in⁃ creases with fluctuation. Within a certain depth below the ground，the growth of subgrade settlement gradu⁃ ally slows down. During the 20 years of train operation，the maximum cumulative settlement reached 18.15 mm，which met the 30 mm required by the embankment section in the high-speed railway design code.

Key words: high fill subgrade, train loading, dynamic response, FLAC3D