The influence of the cross section on the initial compression wave is studied by using the moving model experiment in this paper. The results show that the initial compression wave variation is the combined result of the average cross-sectional area and the cross-sectional area distribution of a high-speed train streamlined nose when the train's max cross section and the streamlined nose length are the same. The average cross-sectional area affects the magnitude of the initial compression wave, and the cross-sectional area distribution affects the pressure gradient of the initial compression wave, therefore, affects the pressure dissipation of the initial compression wave propagating in the tunnel.