The invention relates to a steel-structure cluster structure composite member. The steel-structure cluster structure composite member comprises a front member and a rear member which are arranged in afront-rear spaced mode; the front member comprises one or more than two front member units connected together, the rear member comprises one or more than two rear member units connected together, andthe front member units and the rear member units are each an integrally-formed G-shaped steel member; each G-shaped steel member comprises a member bottom plate and member side plates arranged on thetwo sides of the bottom plate; member wing plates are folded at the ends, away from the member bottom plates, of the member side plates in an opposite direction mode; reinforcing edges are arranged at the opposite ends of the every two member wing plates of the same G-shaped steel member in the direction of facing the corresponding member bottom plate in an inwards folded mode, so that the everytwo corresponding member wing plates form a restrained edge; and the corresponding member side plates of both the front member and the rear member are connected through side connecting plates. The front member and the rear member are connected to the overall member through the side connecting plates, the size of the section of the center position surrounded by the front member, the rear member andthe side connecting plates is large, and the torsional strength of the composite member is ensured.