A three-dimensional and steady-state model was developed to explore the effects of fuel gas humidification on cell performance for conventional and interdigitated flow fields in proton exchange membrane fuel cells (PEMFCs). Effects on the current density, temperature difference, and water content have been simulated and analyzed, respectively, with conventional and interdigitated flow field when the humidification in the anode or cathode is from 25% to 100%, respectively. The numerical results show that, when RHa (the anode-side relative humidity) is 100%, the current density decreases as RHc (the cathode-side relative humidity) increases with conventional flow field, but for PEMFC with interdigitated flow field, the current density increases first and then decreases as RHc increases. When RHc ranges from 50% to 75%, temperature difference on the membrane has little change. Membrane water content for PEMFC with interdigitated flow field is higher, with the maximum water content 16.67 at cell voltage of 0.4 V.