Abstract: Site seismic analysis plays an important role in the practical seismic design of underground structures, and the equivalent linear method is a widely-used approach for the seismic response analysis of one-dimensional soil layer. Based on the theory of the equivalent linear method, an equivalent linear method for the seismic design of underground structures is proposed. And the methods to calculate the material properties are also presented. Then the proposed method is applied in the transverse seismic analysis of a subway station. The Davidenkov constitutive model is applied in the time history method as the comparative model. The error between them can meet the requirements of engineering design. The proposed method has advantages of the equivalent linear method and the time-history analysis method for underground structures, which can be used as a time-history analysis method for the seismic design of the underground structures such as subway stations.