In order to assess the safety state of superconducting cables in real-time, this paper proposes a safety state evaluation method for superconducting cables based on system dynamics theory. Firstly, the key non electrical indicators that affect the safety state of the system are selected and a system dynamics flow chart for them is built; Secondly, health indicators related to equipment parameters are obtained and weights are assigned to them; Then, the relationship between equipment health index and failure probability is obtained to conduct real-time safety state assessment of the equipment; Finally, the series system model is used to obtain the fault probability of the superconducting system, and the rationality of the proposed model and technical method is verified through simulation examples. The results show that the proposed method can evaluate the safety state of superconducting cable operation in real time.