In order to research the impact of different reinforcement measures on the seismic performance of the mortise-tenon joints in timber structures, referring to the typical mortise-tenon joint of traditional timber structure in the southwest region of China, five groups of mortise-tenon joint specimens of three types: Tou mortise-tenon joints, Ban mortise-tenon joints, and dovetail mortise-tenon joints were made to carry out the quasi-static test. The four groups were reinforced with iron hook, steel plate, and wood strip(two groups). The seismic performance parameters of reinforced and non-reinforced joint specimens, such as failure forms, hysteretic and skeleton curves, amount of tenon pullout, and energy dissipation, were comparatively studied. The test results show that the main failure modes of the unreinforced mortise-tenon joints were cracking in squeeze of the mortise-tenon and pullout of the tenon. The reinforced joints were mainly damaged by iron hook breakage, steel plate bending-torsion yielding, and wood strip breaking. All the reinforcement measures can effectively increased the bearing capacity of the joint and reduced the pullout of tenon. The reduction ratio of the pullout amount of the reinforced joint was more than 5%. Compared with the iron hook and steel plate reinforcement, the bearing capacity of the joints reinforced with wood strip was improved significantly. After reinforcement, the negative bearing capacity of the Ban mortise-tenon joints and dovetail joints was increased by more than 10 times. At the same time, the energy dissipation of the Ban mortise-tenon joint reinforced with wood strips was increased by more than 2.6 times, and the energy dissipation of the reinforced joint with iron hook and steel plate also significantly improved.