The emergency facilities of a nuclear power plant are those facilities utilized for emergency response purposes. According to relevant documents, nuclear power plants should adopt appropriate measures and provide sufficient information to protect staff in emergency facilities and prevent excessive exposure in accident conditions. Moreover, the habitability of emergency facilities should be evaluated for nuclear power plants during the design and safety analysis stage. Currently, various nuclear power plants in China have provided habitability criteria based on radiation monitoring instruments in emergency facilities, represented by the emergency control center (emergency command center). However, most of them neglect the contribution of internal radiation, and the relevant gamma dose rate thresholds also vary. In response to the lack of practical quantitative judgment standards and universal analysis methods for determining the habitability of emergency facilities in actual accident scenarios of nuclear power plants, this paper takes the emergency control center (emergency command center) of a nuclear power plant as an example to conduct research on the threshold of habitable radiation dose rate for emergency facilities. The main research idea of this paper is to select source terms of typical severe accidents based on the design characteristics of the nuclear power plant, and combine them with the meteorological sequence formed by historical meteorological observation data to calculate the dose level in the emergency control center under various typical accident situations. On this basis, calculate the dose rate level of each dose rate monitoring instrument in the area of the emergency command center when exceeding the habitable dose criteria. Based on probability theory, analyze and determine the threshold of habitable dose rate for each accident situation. Finally, take the minimum value of the dose rate threshold for all typical accident situations as the conservative threshold applicable to any accident situation. The above method fully selects various serious accidents and actual meteorological sequences, and considers both external and internal radiation doses in the calculation and analysis process. The final threshold of habitable dose rate obtained is representative and of great significance for guiding emergency protective measures for personnel in emergency facilities.