Abstract: To improve thermal management performance of proton exchange membrane fuel cells (PEMFCs) in underwater power platforms and to address the slow temperature control response caused by strong coupling and nonlinearity, a dual-actuator cooperative thermal management system based on fuzzy proportional- integral-derivative (PID) control was designed. An electro-thermal coupled mathematical model of the PEMFC was established, and a system simulation platform comprising the stack, water pump, and radiator was constructed. Results show that under dynamic current conditions, compared with conventional PID control, the fuzzy PID controller achieves faster and more stable stack temperature regulation by adjusting the water pump flow rate and radiator airflow in real time. The fuzzy PID reduces the temperature stabilization time by 323.1 s, lowers overshoot, improves efficiency, and maintains temperature control error within ±0.05 K. The system significantly enhances the robustness of PEMFCs under complex operating conditions.