In order to provide fast, accurate and effective fault isolation procedure and improve the level of aircraft maintenance support, the method of fault isolation procedure analysis based on system schematics and dynamic fault tree is studied in view of the lack of integrity and logic of traditional fault isolation procedure analysis. Taking the fault of the bleed air overheat detection system of an aircraft fire protection system as an example, the system design schematics and fault alarm logic analysis are carried out in depth, and a dynamic fault tree with sequence correlation, function correlation and backup relationship is constructed by using dynamic logic gates, and then correlation fault analysis and troubleshooting flow chart transformation are carried out. The results show that the method can systematically and comprehensively reflect the fault trigger logic, provide a fast and effective fault isolation path, and has good application prospect and popularization value in the Line Maintenance field of complex aircraft systems.