Abstract: In the paper, the three composite concrete two-way slabs of SXB-1, SXB-2, and SXB-3 reinforced with cold-formed thin-wall square steel tubes and with a density of 1 600 kg/m³ of foam concrete were tested and compared by FEM simulations. The failure phenomena of the three composite two-way slabs and the mechanical performance of the composite concrete two-way slabs were got. Influence of different spacings of tubes on the baring capatity performances of composite concrete two-way slabs was analyzed. Taking as the wall thickness of the section steel tubes, the strength of the section steel, and the spacing of the section steel as control variables, the effect on the mechanical properties of the composite concrete two-way slab was studied. The results showed that:the composite concrete slabs had good bearing performances in the X and Y directions, and the cracks at the bottom of the slabs at the time of failure eventually showed intersecting butterfly shape or X-shape development; the smaller the section spacing, the higher the stiffness and bearing capacity of the composite concrete slabs, the smaller the deflection and strain; as the section wall thickness increased, the steel material strength increased, the grid sizes decreased, the strength and rigidity of the steel frame itself, increased and the same as the the composite concrete two-way slabs.