Abstract: To improve the shear performance of assembly connections in precast RC shear wall structures, a novel polygon-key assembly connection (PKA connection) is proposed. Pseudo-static tests are carried out to study the shear performance of the PKA connections. Specimens’ parameters considered in the tests consist of polygon-key inclination angles, polygon-key heights and axial compression ratios. Shear capacity, stiffness, and failure mode of the PKA connections are investigated. Furthermore, theoretical analyses of the PKA connections are performed, equations for calculation of PKA connections’ shear capacity are deduced, and the theoretical analysis results are validated by the test results. The results show that the polygon-keys can effectively improve shear capacity of the PKA connections. Compared with parallel assembly connections, peak loads of the PKA connections are enhanced by more than 15%. When polygon-key inclination angles are within the range of 45° ~ 90°, peak loads of the PKA connections change slightly. When polygon-key heights are within the range of 5 cm ~ 7 cm, cracking loads and peak loads of the PKA connections change slightly. With an increase in the axial compression ratio, peak loads of the PKA connections gradually increase. Based on the shear-friction theory, calculated peak loads of the PKA connections are in good agreement with the test results.