Abstract: The station black-out (SBO) is a typical initial incident which may lead to severe accident. In order to study the ability to deal with SBO accident in M310 type nuclear power plant and consider the requirements of Fukushima improvement actions, MELCOR code was used to analysis mitigation ability to the SBO accident. To get the key point of the impact in SBO accident process, the factors of main pump seal, steam-driven auxiliary feed water, and feed water into primary and secondary circuits were studied, and the equipment availability and the revamping time were also taken into account. The results show that the improved M310 type nuclear power plants can mitigate the SBO accident effectively and the reactor can be cooled to controllable state to avoid the massive release of radioactive material to environment.