Since the initiation of social stability risk assessment in China in 2012, risk levels have primarily been determined using the single-risk-factor method and the comprehensive risk index method. However, current research on these methods is insufficient to effectively guide the social stability risk assessment of nuclear power projects. This paper proposes a method for determining the acceptable social stability risk levels of nuclear power projects to guide their assessments. By studying the practical application of the single-risk-factor method and the weight factors in the comprehensive risk index method, this paper establishes a scientific and credible approach for assessing the social stability risk levels of nuclear power projects. Using a specific nuclear power project as an example, the effectiveness of the proposed method is demonstrated and validated.