Abstract: At present, Level 2 PSA release category source terms are used more and more in the emergency facility habitability analysis, but there are no clear guidance from regulations and standards on how to select the release categories（RCs） source terms, and the practice of the industry is not unified.This paper investigates the source term selection method of the emergency facility habitability analysis of the advanced generation Ⅲ reactors in the world, and puts forward the method and process of selecting the source term of severe accidents in the emergency facility habitability analysis based on the Level 2 PSA release categories. Taking the emergency command center of an advanced PWR nuclear power plant as the object to study, four different source term selection schemes are given by using the method proposed in this paper, and the effective dose of the staff in the emergency command center is calculated. Through the performance evaluation method, two optimal selection schemes of Level 2 PSA release categories are recommended, which provide guidance for the selection of severe accident source terms in the emergency facility habitability analysis.