Abstract: Aiming at the cracking of high-pressure filter oil inlet duct and the fracture of filter support fixation rivets in the aircraft hydraulic system, the fault cause was analyzed by means of macro and micro observation, metallurgical structure analysis, hardness testing, etc. The structure characteristics and working conditions of the high-pressure filter position were also considered. The results show that the crack mode of the oil inlet duct is fatigue crack, which is due to an abnormally large load in the lateral direction of the vector. The fracture mode of the filter support fixation rivets is fatigue fracture, which is because the actual load situation of the high-pressure filter position is more complex, and the fatigue margin is insufficient. The fatigue cracking of the oil inlet duct is caused by abnormal vibration after the fracture of the rivets, so it is the victim. It is suggested that the actual load condition of the high-pressure oil filter position should be checked and effective measures should be taken to improve the structural stability and fatigue property.