In recent years, laminated floor has been widely used in prefabricated buildings. Due to the limitation of the current construction technology of prefabricated layer and cast-in-place layer, the laminated floor is too thick as a whole. This problem is expected to be solved by seeking a kind of laminated board external tool technology and efficient construction technology. In this paper, the rigidity and bearing capacity of the prefabricated bottom plate are improved by using the external section steel technology, so as to reduce the thickness of the prefabricated bottom plate and the castin layer. The feasibility is verified from two aspects of technical principle and technology, and the technical advantages and disadvantages of the process are analyzed, including economic benefits, time costs, social benefits and technical difficulties. It is feasible to improve the stiffness and bearing capacity of the prefabricated bottom plate by using the technology of external section steel, and to ensure the force of the prefabricated bottom plate in the construction and demudding stage theoretically. From the technical process, the use of prefabricated bottom plate attached steel technology has increased the steps in the factory production process, increased the transportation times and transportation risks in the storage yard transportation, but reduced the workload in the construction stage, and the overall process is feasible.