Two test models of T-typed short-limb shear wall coupling beam in a scale ratio of 1:3 have been designed and fabricated. Firstly, low cycle reciprocating load is applied to the two models so as to make the coupling beams suffer different degrees of pre-damage at the end, i.e., the coupling beams experience different degrees of bending failure at the joints. Under the condition of not removing the axial force of the wall body, high performance composite mortar (CTRM) reinforced by carbon fiber mesh is used to strengthen the bending resistance of the damaged part of the beam root, with the low cycle reciprocating load applied to explore the flexural bearing capacity, crack resistance, stiffness, ductility and energy dissipation capacity of the reinforced short-leg shear wall coupling beam after reinforcement. The experimental results show that CTRM is a very effective method to strengthen the coupling beam of short-limb shear wall coupling beams; compared with the original structure, the seismic performance of the damaged beam ends or wall-beam joints can be well restored or even improved by the reinforcement layer; the lighter the earthquake damage is, the more obvious its improvement will be. A further finite element analysis has been carried out of the test model before and after reinforcement, with its results in good agreement with the test results, indicating that the finite element analysis model is characterized with a good reliability.