Abstract: To investigate the seismic behavior of unreinforced masonry walls strengthened with high ductile concrete (HDC) layers, three brick masonry walls strengthened with HDC layers, one brick masonry wall strengthened with steel-meshed cement mortar, and one brick masonry wall served as the reference specimen were designed. The failure pattern, hysteretic characteristics and energy dissipation capacity were studied through the quasi-static tests. The test results show that the HDC layers can provide a constraining effect for the wall, effectively delay the generation of cracks, change the failure mode and improve the lateral strength and ductility of the wall. After being strengthened with a single HDC layer, the cracking load and energy dissipation capacity of the wall is obviously higher than that strengthened with steel-meshed cement mortar and the bearing capacity decreases slowly. A calculation method is proposed to estimate the ultimate lateral strength of strengthened masonry walls and the accuracy of the method is validated by the test results.