Abstract: Similar to the multi-grid composite wall reinforced by steel bars, an improved multi-grid composite wall reinforced by light steels is proposed, where the steel bars in grid beams and columns are replaced by light steels. To apply the improved composite in large-bay high-rise buildings, its seismic performance should be examined. 1/2 scale multi-grid composite walls reinforced by light steels, as well as by steel bars, were tested under reversed cyclic loading. Damage procedures, load-bearing capacity and ductility were compared. It is found that both kinds of walls fail in shear, and the damage propagates from the filling blocks to grids made up of grid beams and columns, and finally to the edged frame. Compared with using steel bars, using light steels to reinforce composite walls, with a 17% increase of steel, generated a yielding capacity of 54.3% larger and an ultimate capacity of 53.1% larger. The stiffness behavior and energy dissipation capacity of the improved composite wall were better too, while the ductility capacity of the two composite walls was almost the same.