Abstract: A viscoelastic damper is proposed for the reinforcement of mortise and tenon joints in traditional wooden structures in this study. The device can be used to reinforce mortise and tenon nodes in three ways: single-supported, single-supported with pins and double-supported. To compare the effects, and the mechanical properties of the damper, the reference joint and, the reinforced joint were tested in turn with low cyclic loading technique. According to the tests, the changes of several seismic performance indexes of the reinforced joints were analyzed, and the bending moment-rotation model of the enhanced joints was deduced from the geometrical deformation characteristics of the joints. And it is concluded that: the viscous-elastic damper showed good fatigue resistance and energy dissipation capacity under reciprocating loading; the hysteresis curve of single-supported reinforced joints shows "pinching" segments, while the hysteresis curves of single-supported with pin and double-supported reinforced joints are full and symmetrical, and the latter two types of reinforced joints have a more significant improvement in seismic performance. Under the three application modes of single support connection, of single support with pin, and of double support connection, the maximum moment bearing capacity of the joint is increased by 0.6, 1.0, and 2.1 times, respectively, the average stiffness is increased by 0.1, 0.67, and 1.24 times, and the total cumulative energy dissipation is increased by 0.04, 0.93, and 1.58 times. Moreover, the predictions of the moment-rotation theoretical model for the reinforced joints are in a good agreement with the experimental results, which is provided a solid theoretical foundation for the application of support-type connection of viscoelastic dampers in the traditional wooden structures.