Abstract: Autoclaved aerated concrete (AAC) block masonry wall has the characteristic of light weight but poor aseismic performance. High ductile concrete (HDC) layer and strip were used for improving the aseismic performance of AAC masonry load-bearing walls. Four unreinforced masonry walls and two confined walls were designed. Among these specimens, two specimens were strengthened with single-sided HDC layer and two specimens were strengthened with HDC strips. The effects on the failure patterns, the hysteretic performance, the lateral strength and the deformability of each specimen were studied by a quasi-static test. Test results show that the single-sided HDC layer can change the failure modes of AAC masonry walls. For unreinforced masonry walls, HDC can significantly reduce the cracks and improve the stiffness degradation, the lateral strength, the deformability and the energy consumption capacity of AAC masonry walls. For confined masonry walls, the lateral stiffness, the horizontal bearing capacity and the energy consumption capacity of the confined wall strengthened with single-sided HDC layers were greatly improved, with high residual bearing capacity and slight damage. Based on the failure mode of specimens, a method for calculating the horizontal bearing capacity of strengthened walls is proposed, and the calculated results are in a good agreement with the experimental results, which can provide a reference for the calculation of bearing capacity of AAC block walls strengthened by HDC.