Study on the pool sodium-cooled fast reactor which has two loops, the level 1 probabilistic safety analysis of internal events under power operation condition is completed. Based on the design features of the plant and the accident progression, the initiating events are identified and the event tree is built up, and finally the core damage frequency is calculated. According to the results of Level 1 PSA, the key factors for core damage frequency are identified, and in connection with the design of the plant, some insights and recommendations are also provided. The results show that the total core damage frequency is 1.09E-07 per reactor-year. According to the contribution of 20 initiating event groups to the total core damage frequency and the minimum cut set analysis, it is found that the main contributor to the risk of sodium-cooled fast reactor is the decay heat removal system. Therefore, improving the reliability of the decay heat removal system is very important for the safety of the power plant, and the damper is the only active equipment in the decay heat removal system. It is suggested that the damper should be designed with diversity to reduce the effect of common cause failure and improve the reliability of the system.