The mechanical model of segment joint, which can simulate the characteristics of complex joints, is used to analyze the mechanical effects of different positions, sizes and numbers of sealing gaskets on segment joint. The design of joints considering the stress of segment joint and waterproofing of sealing gaskets is discussed, and the corresponding improvement suggestions are given. The study results show that: (1) For the segment joint in weak stratum, the segment joint can hold a high bending stiffness, the risk of concrete collapse and bolt yield can be reduced, the mechanical safety of segment joint can be guaranteed, and the joint waterproofing performance can be improved by arrange the sealing gasket close to the middle of joint surface. (2) For segment joint in hard stratum, to achieve the same effects, the sealing gasket should be arranged close to the edge of joint surface, or the sealing gasket with largewidth should be adopted, and the joint surface contact mode and bolt material should be improved.