A reinforced truss concrete composite slab with a built-in hollow thin-walled box was proposed, which combined the advantages of the cast-in-place hollow slab and the prefabricated reinforced truss concrete composite slab. Static full-scale model bending performance tests were conducted on five reinforced truss concrete hollow composite slabs and a reinforced truss concrete cast-in-place hollow slab under monotonic load. The failure mode, bending bearing capacity, overall working performance of the section, crack distribution, steel strain, and concrete strain of the plate were analyzed. Results showed that under regular use, there was no horizontal crack along the composite surface of the laminated hollow slab, and the coordination performance between the prefabricated layer and the cast-in-place layer was good. The failure process conformed to the characteristics of suitable reinforcement failure. Multiple evenly distributed cracks appeared at the bottom of the board, resulting in good overall deformation performance. Composite hollow slabs still had sufficient load-bearing capacity and safety reserves after cracking. The experimental and theoretical values of the ultimate bearing capacity were consistent, with an error of within 6.0%, meeting the specifications. The overall stress performance of the prefabricated composite hollow slabs with the same size and specification was relatively similar to that of cast-in-place hollow slabs, so both of them could meet the engineering design requirements.