In order to study the flexural performance of cold-formed thin-walled steel-fine aggregate concrete composite beams, static tests were carried out on three composite beams with different shear structures. The failure mode and bearing capacity of composite beams were investigated. The failure characteristics of composite beams include shear failure and torsion of joist web, plastic yield of upper flange of the joists, pull-out of part of the shear screws and cracks in concrete, which lead to overall failure of composite beams. The test results show that setting shear connectors has insignificant effect on the ultimate bearing capacity, but can increase the bending stiffness. An ANSYS finite element model is established for numerical simulation as well as parametric analysis based on the calibrated model. The results show that reducing the screw spacing, increasing the strength of steel, increasing the web height of joists or the thickness of concrete can improve the bearing capacity. Bending bearing capacity formulas with a modified coefficient which considers the influence factors of the web height of joists and screw spacing are proposed. The accuracy of the proposed formulas is verified by comparing the theoretical calculation results with the experimental results and finite element analysis results.