With the long-term operation of the aircraft and the gradual increase of the age of the aircraft, multiple factors such as wiring harness expansion and contraction, vibration and so on may lead to the failure of the aircraft wiring harness. This paper starts from the actual failure phenomenon of the aircraft and analyzes the failure mechanism. The fault mechanism was simulated by the thermal simulation of the wire harness, and the factors affecting the thermal temperature rise of the wire harness were analyzed. According to the results of the simulation, laboratory experiments were carried out to reproduce the fault process and fault phenomena, and the effectiveness of the simulation method was verified. A reliability prediction method based on the influence of core damage degree and wire harness temperature rise is proposed. It provides guidance and suggestions for the impact hazard assessment and reasonable selection of maintenance methods when the aircraft conductor is damaged.