Civil aircraft fuel tank system ignition resource prevention is the important part in the fuel tank explosion prevention. According to FAR 25.981 and FAA AC, the fuel tank system ignition resource prevention analysis method was studied. For the general requirement of ignition resource prevention, the analysis methods mainly include identification of failure mode of ignition source prevention design feature, confirm whether if it is intrinsically safety design, and using various analysis methods such as qualitative analysis and quantitative analysis to determine whether it can meet the requirements of the ignition source prevention. Finally, CDCCL is formulated to meet the requirements of continuous airworthiness. In addition, the failure mode, inherent safety design, quantitative analysis and Continuous Airworthiness were analyzed and explained. For example, all the failure modes that may produce ignition source should be sorted out for failure mode, and then safety analysis should be carried out one by one. For the ignition resource caused by lightning, the fault tolerance design or non-fault tolerance design must be defined. If it is a fault tolerance design, it can only be verified to be reliable and effective. If it is non-fault tolerance design, qualitative analysis or quantitative analysis should be carried out according to the corresponding situation.