Abstract: Mortise and tenon joints are widely used to connect components of traditional timber structures, and their hysteretic curves show highly nonlinear characteristics under reversed cyclic loads. To accurately characterize the unique hysteretic behavior of mortise and tenon joints, an improved hysteretic model considering hysteretic damage was proposed, which considers slip characteristics and strength degradation during reloading. Based on the hysteresis test of straight mortise and tenon joint and semi-tenon timber frame, the proposed model accuracy was discussed and the joints energy dissipation capacity degradation was analyzed. The shape parameter sensitivity was discussed, and a suitable parameter range for straight and semi-tenon joints was proposed. Based on available tenon bending analysis methods, a theoretical solution for the hysteresis model envelope curves was proposed, which reduces the dependence on experimental tests.