With military training intensity being comprehensively improved, there are dangerous oil leakage, and cracks in hydraulic duct of fighter jet, these phenomena threaten to flight safety. Aimed to the problems thatthere are some mismatches between the fatigue life on the rear fuselage hydraulic conduit and the life of the body structure, this research is focused on one main influence factor, the assembly error. At the start of the fatigue life analysis of random vibration load, applying digital modeling methodology to develop the typical pipeline model, based on the Miner linear cumulative damage theory, the fatigue calculation program is developed by finite element analysis software to simulate and evaluate the fatigue life of normal assembly hydraulic conduit. Based on the influence of assembly stress on fatigue life, the pipeline model is adjusted to simulate different assembly errors, and the fatigue life of hydraulic ducts with different assembly errors is analyzed by using structural dynamics theory and fatigue calculation program. It follows that when the assembly error is greater than 0.73 mm, the fatigue life of the hydraulic duct will be lower than the airframe life of 3000 flight hours, i.e. seriously threatening flight safety. The research results provide technical support and experience reference for the further research on the theory of aerohydraulic pipe assembly.