One of the novel resistant systems to lateral loads is the use of composite shear wall, which is made up of a thin steel plate, with concrete cover on one or both sides. The utilization of this kind of wall is increasing due to its stiffness, high resistance, and also appropriate ductility. Research indicates that the existence of a gap between the steel frame and the concrete panel has deep impacts on the amelioration of wall behavior and its ductility. In this paper the influence of the gap between the concrete panel and the frame, on the behavior of the composite shear wall has been investigated. For this purpose, a nonlinear static analysis for various models of composite shear walls, with the span of 3, 4.5, and 6m, and different gaps have been done, and relationship between behavior of wall with different width and the number of stories has been studied. The results indicate that gap width of 50-80 mm between the concrete panel and the steel frame, has improved the ductility, ultimate strength of composite shear wall.