The Supervisory Control and Data Acquisition (SCADA) system of the energy storage system is the main target of cyber attacks, and its failure and its interaction with the physical system are the difficulties in the reliability evaluation of the energy storage system. To this end, for different cyber attack scenarios of information systems, the Bayesian attack graph method is used to establish the cyber attack process model of the SCADA system, and the average failure time of the target components of the SCADA system is calculated for different attacker skill levels; A reliability evaluation method based on Monte Carlo simulation is proposed, and a reliability evaluation model of energy storage system is established considering the failure of target components of SCADA system caused by cyber attacks and their interaction with the physical system; The normal operation availability rate and power loss value of the energy storage system under different scenarios are calculated. The results of the analyses can provide a theoretical basis for the operation and risk management of energy storage system.