The invention provides a combined-type prefabricated hybrid beam and stiffened column mounting structure and method. The structure comprises hybrid beams, stiffened columns, longitudinal ribs, hoops,H-shaped steel, connecting plates, welding end sockets, fixing plates, outer partition plates and lap joint blocks. The method comprises the following steps of mounting of the stiffened columns and hoisting of the hybrid beams. The combined-type prefabricated hybrid beam and stiffened column mounting structure and method have the advantages that on-site hoisting construction is facilitated, and the problem that bars are exposed out of the two ends of existing hybrid beams, and consequently on-site mounting is extremely inconvenient is solved; components are prefabricated through factories, andthrough the industrialization assembly-line production mode, the production efficiency of the components is improved; and connecting structures of the components are simple, and the components are low in manufacturing cost, beautiful and practical.