Degradation of bond performance is one of the main factors that lead to the decrease of mechanical properties of corroded reinforced concrete members. Based on experimental study of bond behavior of corroded components and cohesive zone model, a bilinear cohesive element with thickness was established. A separation reinforced concrete beam analysis model was established and bonding interface layer was introduced in this paper to study the bonding performance degradation effect on the flexural stiffness of corroded RC beams. The results show that the bilinear cohesive element can effectively simulate the bond mechanism between steel and concrete. Moreover, the influence of the degree of corrosion on the bond performance can be reasonably described by the thickness of the bonding unit which is decided according to the depth of corrosion. Furthermore, numerical analysis results is compared with the experimental data and the theoretical results calculated by experiential method, and the results show that the method in this paper is effective and reasonable.