Abstract: A severe accident model of typical M310 nuclear power station with MELCOR 1.8.5 code was constructed in this paper. Based on the model, several passive safety measures were designed, and their benefits of mitigating the accident caused by station blackout (SBO) were simulated. The calculating results show that the core makeup tank system, external reactor vessel cooling system and passive residual heat removal system can operate successfully in SBO, postpone the progression of the accident markedly, stabilize the M310 nuclear power station in a safe state and gain more time for manual intervention.