Abstarct: The corrosion of reinforcement bars embedded in concrete is regarded as the most important factor in reducing durability of RC structures in aggressive environments such as marine environments. Study on corrosion mechanism indicates that corrosion products are accumulated around reinforcement in RC structures by passing time and increasing corrosion’s speed. This phenomenon reduces the bond strength between concrete and reinforcement bars; therefore, it causes deterioration in structures under service load. In this study, the effect of corrosion on the bond strength of RC structures is investigated via Finite Element Method (FEM) for which ABAQUS software was employed. First, a pull-out specimen and a three-point bending test of an RC beam were modeled. Numerical results of this model were compared with the test results. After acquisition of the convergence between the model and experimental results, the effect of different corrosion levels were studied by considering nonlinear behavior of bond strength in reinforced concrete. Results revealed that the ultimate bond strength of RC structures is strongly affected by corrosion levels. Although the ultimate bond strength is increased by starting corrosion procedure, significant reduction in bond strength is observed in further progression of corrosion.