Abstract: Through in-situ test on the test plot of lime-swelling soil filled subgrade for the high-speed railway from Hefei to Nanjing, the dynamic response of the subgrade under different velocity is researched by simulating and field-testing the deformation and accelerate caused by running trains in different speed. By testing the deformation, accelerate and dynamic strain on different plots, the distribution law of the deformation,accelerate and dynamic strain is found. It is revealed that the value from the existed code is not reasonable, so a new fixable value for over 200km/h railway is obtained which given reference to the design of new-build high speed railroad.