Abstract: To study the seismic behavior of flexural unreinforced masonry walls strengthened with High Ductility Concrete (HDC) overlays, an unreinforced brick wall, a wall retrofitted with steel-meshed cement mortar and three walls strengthened with HDC overlays were designed. Quasi-static tests were performed to study the failure mechanism, hysteretic characteristics and energy dissipation capacity of the brick walls. The results shows that:the bonding properties between the HDC overlays and brick walls are excellent, and the HDC overlay is effective to limit the crack and damage and avoid brittle failure; the HDC overlay has good restraining effect on the brick walls and improves the seismic performance of the brick walls; the HDC overlay can significantly improve the damage tolerance and deformability and reduce or avoid the repair expenses after earthquakes. Its effectiveness is better than a traditional steel-meshed. According to the statistical analysis, this paper gives the fragility curve based on the drift of walls strengthened by HDC layers.