With the deep integration of industry and information technology, the continuous development of information technology makes the traditional relatively closed and relatively safe industrial control system exposed to network attacks, viruses, Trojan horses and other network security threats. In the field of nuclear power, once the industrial control system is attacked, it is very easy to affect the progress of scientific research and production, product quality decline, equipment damage and even casualties and a series of operational security incidents or information security incidents such as leakage. Taking an effective risk assessment method to evaluate the safety of the industrial control system is conducive to identifying the effectiveness of the industrial control system and finding out the weak link of the system, so as to effectively prevent the possible risks. Based on the analysis of the industrial control system in the field of nuclear power, this paper establishes a safety risk assessment model based on analytic hierarchy process, and establishes a safety risk assessment model according to analytic hierarchy process. Through a simulation case of the simulation experiment platform of Hebei Nuclear Security Technology Innovation Center, the simulation verification analysis of the evaluation method was carried out to provide data and technical support for effectively dealing with the network threats faced by the industrial control system of nuclear facilities.