In order to improve the design efficiency of wedge segment assembling and fitting of shield tunnel, the geometry structure model of segment is established and fitting principle of the tunnel design curve is analyzed. By conversing the segment parameters, standard library for the parametric modeling of wedge segment of shield tunnel is built. After analyzing the computational relationship of design functions and editing script, the parameter fitting of tunnel curves is realized by partly transforming coordinate system, and then the segment layout fitting procedures is edited and applied to analyze the effect of different wedge qualities on the fitting curve of wedge segment of shield tunnel. The shield tunnel segments with the origin design diameter of 14 m, used in the rehabilitation project of Xiasha Section on Genshan fast road in Hangzhou, are layouted by models; and the results show that the layout procedure can meet engineering needs, and can provide references for practical projects.