Given the subjectivity and uncertainty of the credibility quantification of complex guidance simulation system, an evaluation model of simulation credibility based on DS evidential theory and gray cloud cluster is proposed. Firstly, the experts′ opinions are obtained by AHP, and different opinions are combined by DS to obtain the index weight of higher credibility. Then the gray cloudclustering model is adopted to quantitatively processing the qualitative results as the whitening weight function in grey clustering. The credibility of the simulation system is evaluated by calculating the gray clustering coefficient. Finally, the evaluation of the HILS simulation system is carried out and the results show that the model is feasible and practical. This model provides a new and effective way for the simulation credibility evaluation and comprehensive evaluation.