The changes of tunnel rock stress caused by dynamic load is a hot point in geotechnical engineering. The paper introduces seismic methods of seismic design codes in China. The paper select state road 318(Huangcaoping part)as an example. Using finite difference software to analyze the rock pressure changes around the lining-tunnel with different seismic inputs. Comparing the results the rock static pressure and find the relative amplification factor between dynamic pressure and static pressure. Based on the results of analysis, we can obtain the following conclusions: As the peak ground motion acceleration increases, the peak value of tunnel rock increases, too. The amplifications change in a small range. The oblique parts of tunnel are the weakest parts of the tunnels. In different areas, the amplifications change a lot. The maximum ones are in the area of oblique.