AbstractNowadays, civil transport aircraft designers attach importance to designated fire zone and always ignore the flammable fluid leakage zones, which may threaten the safety of aircraft. The main content of the research are as follows: Firstly, this paper starts from the civil transport category aircraft flammable fluid related airworthiness requirement (§25.863), including the research of development background, related advisory circular and main general compliance verification method. The compliance verification process of §25.863 is given. General protection measures include drainage and ventilation, separation and isolation of leakage from ignition sources, component qualification, cooling air ducts, condition monitoring, detection and accommodation, and fire protection. Secondly, design considerations and compliance verification methods of the systems of the civil transport aircraft are given. Finally, in view of the characteristic of the typical civil transport aircraft configuration, zonal safety analysis method is adopted to research the source of ignition control requirement and method, the ventilation and draining design requirement and method. The research product is used for the fire protection design and the compliance certification of the airworthiness requirement of civil transport aircraft flammable fluid leakage zone.