The Forchheimer's inertial force impact is always neglected when studying the mass transfer of proton exchange membrane fuel cells in previous literatures. In this work, firstly, driving forces affecting liquid droplets on gas diffusion layer surfaces are analyzed, and it is found that the impact of Forchheimer's inertial force becomes non neglected when the Reynolds number is increased. Therefore, a two-dimensional, non-isothermal, steady-state and modified two-fluid model, which considers the Forchheimer's inertial force impact, is developed for the first time. The modified two-fluid model is validated by comparing with experimental data and conventional two fluid model results. The results indicate that the modified two-fluid model results can match the experimental data quite well under various flow rates in both the fuel cell with a straight flow channel and that with a baffled flow channel. Moreover, the liquid water saturation distribution is also studied by using the modified two-fluid model. When considering the Forchheimer's inertial force impact, comparing with the conventional two-fluid model results, liquid water saturations in flow channels, gas diffusion layers and catalyst layers are reduced by 5.69%, 5.56% and 4.22%, respectively, in the proton exchange membrane fuel cell with baffled flow channels.