Air-cooling polymer electrolyte membrane fuel cells (PEMFCs) have shown great application potential in unmanned aerial vehicles (UAVs) for parcel service, disaster relief, and rescue missions. In this work, we develop a kW-level air-cooling PEMFC powered integrated propulsion system for UAV with an inclined cathode flow structure, and evaluate the performance of the integrated propulsion system. The simulated and experimental results show that the integrated propulsion system can directly use the airflow behind the propeller to feed the PEMFC cathode and discard the parasitic power caused by the axial fan in the PEMFCs. The thrust loss of the ICF structure is only 3.6%, which increases the power-to-weight ratio and thrust-to-weight ratio of the integrated propulsion system by 25.9% and 21.8%, respectively. Besides, the integrated propulsion system with the DC-DC module and the Li-ion battery pack shows great dynamic response performance in the power range of 0–2 kW.