Abstract: The quality and the safety in spacecraft AIT stage have an unpredictable impact on the quality, the schedule, and the cost of the spacecraft development process. So an engineering method of risk identification and prevention to evaluate the safety of key processes in AIT is needed in order to improve the safety risk control ability for spacecraft. In this paper, we use the fuzzy comprehensive evaluation and analytic hierarchy method to construct a spacecraft assembly safety evaluation model. Based on the expert scoring, combining with the multilevel fuzzy comprehensive evaluation method and the direct scoring method, the weights of each evaluation index are analyzed and determined. After calculation, the risk value of the key activities for the spacecraft assembly process is obtained.