By using finite element method, a series of parametric studies is performed for the maximum wall deflection induced by excavation in soft clay. Five main parameters effecting deformation i. e. excavation depth(H), excavation width(B), system stiffness(S), axial stiffness of the supporting structure(Sa), ratio of the average shear strength over the vertical effective stress , are analyzed. Based on the results of parametric studies，a simplified calculation method for maximum wall deflection is proposed using multiple regression. The proposed method is verified through several case stdudies. The proposed method can be used to preliminarily predict and also check the final results of design.