Abstract: To solve the problem of anti-seismic capacity decline of aging mortise and tenon joints, four types of flat steel reinforcement devices were designed and manufactured based on the reversibility, nondestructive and intention of preserving the semi-rigid characteristics of mortise tenon joints. The devices were distinguished from each other in whether with a moveable slot and the reinforcement was fixed to the column or not. The flat steel reinforcement devices were applied to half tenon joints through tenon joints and dovetail joints. 12 tenons and mortise joints were designed and manufactured according to the Fabrication Methods of Song Dynasty, including 4 half tenon joints, 4 through tenon joints and 4 dovetail joints. The scale ratio was 1:3.52. All the joints were slightly damaged by cyclic loaded before the low-cycle reversed loading experiment was carried out. The seismic performance parameters of joints such as reinforcement load-displacement hysteresis loops, skeleton curves, degradation of rigidity and energy dissipation capacity were compared and studied before and after reinforcement. The results show that all the hysteresis loops of joints have obvious pinch effect which indicates slippage occurred between the mortise tenon joints and the semi-rigid characteristics of joints were reserved after reinforcement.The energy dissipation capacity of the joints grows in a parabolic way with the increase of displacement loads. The rigidity, peak load and energy dissipation capacity of the joints were improved after reinforcement. The reinforcement effect of the strengthening devices which was fixed to the column was better than others. The results show the seismic capacity of mortise tenon joints can be effectively improved by strengthening the connection between reinforcement and wood components. Finally, suggestions on how to further enhance the reinforcement effect of the four types strengthening devices were put forward.