The invention relates to the technical field of building construction, and discloses a composite floor slab. The composite floor slab comprises two stand columns and a composite floor slab body, transverse plates are arranged on one sides of the outer surfaces of the two stand columns, positioning piles are arranged on the upper surfaces of the transverse plates, a positioning ring is arranged on one side of the composite floor slab body, and the inner wall of the positioning ring is in clearance connection with the positioning piles. A clamping groove is formed in one side of the composite floor slab body, a clamping block is arranged on the other side of the composite floor slab body, and inserting grooves are formed in one sides of the transverse plates. The invention further discloses a composite floor slab connecting method. The composite floor slab connecting method comprises the following steps that S1, the positioning piles are prefabricated; S2, support installation is carried out; S3, the composite floor slab is hoisted; S3, the composite floor slab is hoisted; S4, a cable rope is installed; S5, positioning, connecting and installation are carried out; and S6, the composite floor slabs are clamped. The composite floor slabs can be positioned, connected and installed, so that the connecting efficiency of the composite floor slabs is higher, certain creativity is achieved, the connecting mode is safe and efficient, the construction cost is reduced, and the construction efficiency is improved.