Abstract: When a high-speed train passes through a tunnel, the pressure waves are produced, and lead to some problems, such as the passenger comfortableness and fatigue strength of train. At home and abroad, a lot of numerical and experimental studies have been conducted on tunnel pressure waves. Based on the understanding of the formation mechanism of the tunnel pressure waves, and the foreign scholars' method for the pressure waves in the plain tunnel based on characteristic wave in recent years, the paper develops the calculation method of wave superposition for tunnel pressure waves, where the tunnel pressure wave is supposed to be superposed by some characteristic waves. The result of this method is in good agreement with foreign field test result. Subsequently, using the method of wave superposition, the paper simulates the cases that have different blockage ratio, train speed and length of tunnel. By the comparison between these results and the calculation ones by the method based on one-dimensional unsteady compressible non-homentropic flow model and the method of characteristics of generalized Riemann Variables, the proposed method can be available to the prediction for pressure waves with the train speed of 150~400 km/h, the blockage ratio of 0.09~0.18 and the tunnel length of 0~20 km. This calculation method is more conducive to the understanding of the mechanism of pressure waves, avoids the complex process of numerical solution, and requires lower computational efforts. However, it cannot be used to calculate the gradient of pressure because the effect of gasflow is not take into account.