Abstract: The refueling period of sodium-cooled fast reactor is shorter than that of general light water reactor due to the high neutron flux and high coolant operating temperature. At the same time, sodium-cooled fast reactor can only be refueled root by root due to the requirement of air isolation in the refueling process and the complexity of the refueling system itself, which makes the total refueling time longer than the light water reactor. The reliability of each part of the refueling system of a typical sodium-coolant fast reactor by failure mode and effects analysis, fault tree analysis and other methods were evaluated in this study. At finally, the failure probability of the refueling system during each refueling was obtained, and the reactor operation availability influence by the refueling system failure was also assessed, through analysing the failure probability and recovery time of different failure modes.