A three-dimensional multiphase non-isothermal proton exchange membrane fuel cell（PEMFC）electrochemical model with coupled cooling channels was developed to investigate the effect of Al₂O₃ nanofluids on the heat transfer and output performance of the PEMFC. The heat transfer performance was evaluated by using the average membrane temperature, average membrane water content, and the index of uniform temperature（IUT）, while the feasibility of using Al₂O₃ nanofluids in the PEMFC cooling system was assessed based on net power density and power consumption ratio. The results indicate that Al₂O₃ nanofluids exhibit superior cooling performance compared to ethylene glycol coolant, with particularly enhanced cooling effects at lower coolant flow velocities, significantly reducing the average membrane temperature, thus increasing the average membrane water content. However, while the nanofluid coolant enhances the cooling effect, it may also lead to a decrease in the uniformity of the membrane temperature distribution. Specifically, when the coolant flow velocity was 0.1 m/s and the output voltage was 0.6 V, the average membrane temperature decreased from 359.66 K to 353.10 K, the average membrane water content increased from 9.91 to 11.53, and the IUT rose from 1.71 to 1.96. Al₂O₃ nanofluids can significantly improve the output performance of the PEMFC at low coolant flow velocities, leading to an increase of approximately 3.3% in net power density. Furthermore, under identical cooling conditions, Al₂O₃ nanofluids can enhance the cooling efficiency of the PEMFC while simultaneously reducing the parasitic power caused by the coolant.