The emergency facilities of a nuclear power plant refer to the facilities used for emergency response purpose. According to relevant documents, the habitability of emergency facilities should be evaluated for nuclear power plant. According to relevant documents, the habitability of emergency facilities should be evaluated for nuclear power plant in the design and safety analysis stage. The existing model and method provide the results of habitability assessment of emergency facility from a probability theory perspective, based on conservative meteorological conditions and other input data. It cannot be applied to actual accident scenarios. This paper proposes a complete set of method for habitability assessment of emergency facilities of nuclear power plant in case of nuclear accidents, and then designs and implements a software system based on it. The feedback from application indicates that the method and system fill the gap in this field, effectively improving the level and efficiency of emergency decision-making.