The design of the shiled tunnel segment is one of key and difficult problems in design of subway. The soil round the segments and the joint among them are tow factors must be considerd on the establishment of the calculation model of the segment. Simplification of joint in the calculation model of segment is improved,then a new model is built with the stratum-structure method. Taking Harbin Metro Line No.1 for example, a comparative analysis between the improved model and existing routine model is made. Then some conclusions are got from different deduction ratio of stiffness of joint.The study results show that the new model is tolerable,and significant to design and construction of tunnel segment in theory and practice.