The risk evaluation results of tunnel water inrush based on existing method is fuzzy and the quantification of evaluation index is incomplete. As a result, the existing risk evaluation method for tunnel water inrush is improved and the TOPSIS method is adopted. The comprehensive weighting method formed by analytic hierarchy process (AHP) method and coefficient of variation method considering both the main and objective factors is used. According to the results of the evaluation index classification, four typical samples of risk level are constructed. The risk level of the tunnel water inrush is established based on the samples and closeness degree of the idealized solution. Therefore, the risk evaluation method for tunnel water inrush based on TOPSIS method is established systematically and has been applied to water inrush evaluation of Xiangyun Tunnel on GuangtongDali Railway. The results show that the risk evaluation results of tunnel water inrush based on comprehensive weightingTOPSIS method coincide with the actual excavation results, so as to provide a new method for tunnel water inrush evaluation.