Using a finite element method(FEM) program,a Portland cement concrete slab trackbed(So),and a subtrack asphalt roadbed(RAC-S) were modeled under highspeed train loads to analyze their responses to ground vibration attenuation,by considering 10,15,20,25,and 30 thick sub-track asphalt layer replaced on the top of the upper subgrade.FEM results show that the vibration amplitude of RAC-S is at least three times lower than the vibration for S_0.The maximum vibration amplitude of RAC-S is linearly increased with train speed.The vertical acceleration is found to be reduced by more than 10%when the asphalt layer thickness is increased from 10 to20 cm.However,the reduction in vertical acceleration is only about 1%when the thickness of the asphalt layer changes from 20 to 30 cm.The vibration level is slightly lower if the asphalt layer has higher resilient modulus in the seasons of autumn or winter.This theoretical analysis indicates that a railway substructure that consists of a10-20 cm thick high modulus asphalt layer located at the top of trackbed shows a good performance in ground vibration control for high-speed rails. Using a finite element method (FEM) program, a Portland cement concrete slab trackbed (So), and a subtrack asphalt roadbed (RAC-S) were modeled under highspeed train loads to analyze their responses to ground vibration attenuation, by considering 10,15 , 20, 25, and 30 thick sub-track asphalt layer replaced on the top of the upper subgrade. FEM results show that the vibration amplitude of RAC-S is at least three times lower than the vibration for S_0. Maximum vibration amplitude of RAC-S is linearly increased with train speed. The vertical acceleration is found to be reduced by more than 10% when the asphalt layer thickness is increased from 10 to 20 cm. Less, the reduction in vertical acceleration is only about 1% when the thickness of the asphalt layer changes from 20 to 30 cm. The vibration level is slightly lower if the asphalt layer has higher resilient modulus in the seasons of autumn or winter. This theoretical analysis indicates that a railway substructure that consists of a 10-20 cm thick h igh modulus asphalt layer located at the top of trackbed shows a good performance in ground vibration control for high-speed rails.