To conduct an experimental study of the flexural theory of hybrid steel and fibre reinforced plastic (FRP) reinforced beams, the finite element software ABAQUS was used to model and nonlinearly analyse existing hybrid FRP/steel reinforced test beams. The effects of FRP bar type, concrete strength, and the equivalent reinforcement ratio on the bending performance of hybrid FRP/steel reinforced beams were then studied. Finite element results revealed that the stress expression of FRP bars could be obtained and a formula for the bearing capacity of hybrid FRP reinforced beams could be derived. Finally, experimental data were used to verify the correctness of the formula. Results showed that the equivalent reinforcement ratio had the most significant effect on the bearing capacity and deformation performance of hybrid FRP bars beams, followed by FRP bar type. The strength of concrete had a certain effect on the bearing capacity but had little effect on stiffness. Based on the stress expression of FRP bars in this study, the flexural capacity of hybrid FRP reinforced beams were accurately calculated.