This paper puts forward the main design requirements for the NEA( nitrogen-enriched air) distribution system of aircraft inerting system and analyzes the NEA distribution system of narrow-body aircraft, taking A320 and Boeing 737 aircraft as examples. The NEA distribution scheme of the inerting system of Boeing 787 and A350 aircraft was further analyzed. It was found that the NEA distribution scheme adopts a combination of flow limiting hole, gas nozzle, exhaust flute pipe, and ejectors to achieve the rapid and uniform NEA distribution in the fuel tank. However, these two schemes cannot adjust the air flow in time and actively according to the real-time changes of the gas phase space of each fuel tank, and the optimal design of NEA distribution cannot be realized. This paper proposes a NEA distribution scheme using fuel fluid level for automatic flow adjustment, which achieves the purpose of real-time positive change of exhaust volume with the gas phase space of the fuel tank by arranging a vertical downward exhaust pipeline in the fuel tank and increasing the exhaust holes through the pipeline branches, so as to achieve the effect of adjusting the exhaust volume and exhaust position according to the size of the gas phase space of each compartment. Compared with the NEA distribution scheme of A350 and Boeing 787 aircraft, this scheme could adjust the NEA flow automatically by the fuel level, which is worthy of further in-depth theoretical and experimental research.