Thin steel plate shear wall (SPSW) is a new type of lateral resistance structure suitable for high seismic intensity area, which relies on the tension field formed by the buckling of infilled thin steel plate to resist the horizontal load.It takes a long time to calculate and design SPSW using the detailed model.Thus, in order to improve the efficiency of the SPSW structure design,a simplified model of cross brace-strip model (CBSM)based on the strip model(SM)was proposed to simulate the lateral behavior of diagonally stiffened thin SPSW.The calculation formulas of initial stiffness and bearing capacity of the diagonally stiffened SPSW were derived. The detailed model and the CBSM were established by finite element software ABAQUS. The accuracy of the CBSM and the detailed model were verified by comparing the calculated results with the theoretical formula.The results showed that the detailed model, the simplified CBSM, and the theoretical formula had good consistency in predicting the bearing capacity of the diagonally stiffened thin SPSW with different spans, thicknesses, and stiffener stiffness.It was indicated that the simplified CBSM could accurately predict the bearing capacity of the diagonally stiffened thin SPSW and reflect the contribution of stiffeners to the lateral resistance of the SPSW structure.The theoretical formula of the initial stiffness agreed well with that of the detailed model, and the predicted stiffness of the CBSM was lower than that of the detailed model and therefore proved to be safe.