Abstract: The present precast bottom slab of prefabricated concrete two-way composite floor slab cannot work without the overhanging steel bar, and the cast-in-place strip joint method has disadvantages such as low-efficiency and high cost. In order to solve these problems, based on the previous research on common joints without gap between composite floor slabs, a joint method of pasting carbon fiber composite strips across the bottom of the slab without gap was proposed. Through the static load comparison test of 6 rectangular single-seam two-way composite floor slab connected without gap simply supported on four sides, the flexural properties of CFRP-concrete two-way composite floor slab connected without gap were studied from three aspects:stress characteristics, failure modes, and deformation capacity. The results showed that the four-sided simply-supported composite floor slab connected without gap could achieve two-way force transmission without the phenomenon of crack concentration at the joint; CFRP could effectively participate in the cross-section stress, and contribute significantly to the increase of cracking load of the component and the load value of the test in use. The flexural stiffness of composite floor slabs could be increased by about 25%, and the restraining effect of it on the slab gap was very obvious. The use of polymer mortar to fill the joints of slab could enhance the structural integrity, increase the flexural stiffness of composite floor slabs by about 23%, and reduce the increase of the gap width at the bottom