The phase-field method was used to simulate the propagation of concrete cracks and failure caused by corrosion and expansion of steel bars, which provides ideas for accurate simulation of the corrosion failure process of reinforced concrete (RC) and evaluation of structural durability. In this study, the entire process of corrosion and expansion of steel bars, resulting in cracks and finally falling off of the concrete protective layer, was successfully simulated. The simulation results were in good agreement with the actual observations. By setting different thicknesses of the protective layer, it was found that the thickness of the concrete protective layer had no obvious effect on limiting concrete cracks caused by the corrosion of steel bars. However, increasing the thickness of the protective layer can delay the speed of crack propagation. Simultaneously, considering the corrosion and expansion of multiple steel bars, according to the thickness of the protective layer and the spacing between the reinforcing bars, two forms of wedge-shaped cracking and laminar spalling of the protective layer are simulated. The simulation result is consistent with the actual observation phenomenon. This fully illustrates the possibility of using the phase-field method to simulate the corrosion fracture of RC and provides a reference for the engineering design and durability research of concrete structures.