A one-dimensional two-phase steady model is developed to analyze the coupled phenomena of cathode flooding and mass-transport limitation for a polymer electrolyte fuel cell. In the model, the liquid water transport in the porous electrode is driven by the capillary force based on Darcy's law, while the gas transport is driven by the concentration gradient based on Fick's law. Furthermore, the catalyst layer is treated as a separate computational domain. The capillary pressure continuity is imposed on the interface between the catalyst layer and the gas diffusion layer. Additionally, through Tafel kinetics, the mass transport and the electrochemical reaction are coupled together. The saturation jump at the interface between the gas diffusion layer and the catalyst layer is captured in the results. Meanwhile, the results further indicate that the flooding situation in the catalyst layer is much more serious than that in the gas diffusion layer. Moreover, the saturation level inside the cathode is largely related to the physical, material, and operating parameters. In order to effectively prevent flooding, one should first remove the liquid water residing inside the catalyst layer and keep the boundary value of the liquid water saturation as low as possible.