In order to get reasonable seismic design for silo structures and obtain the practical calculated value of storage side pressure, the “Shi Weixing” calculation method of storage side pressure under the earthquake is introduced at first. Based on the material parameters which can be obtained in engineering design, the revised parameters needed in the calculation of storage side pressure are determined. Then, the numerical model of silo structure is established with ABAQUS to calculate the side pressure variation curve and the correction values of the corresponding parameters are obtained by curve fitting. Modified formulas of side pressure considering silo-storage interaction are summarized by synthesizing different parameters. Finally, the calculated values obtained from the modified formula of storage side pressure are compared with the existing test data and the design values of the code. The results show that the calculated values are in good agreement with the experimental values and can reflect the real and reasonable storage side pressure. Compared with the results, the storage side pressure under the action of strong earthquake is dangerous according to the design value of the code, which means that the proposed calculation formula in this paper is more economical and reliable.