Central Yunnan Water Diversion Project is a strategic infrastructure project for sustainable development in Yunnan Province, and collapse accident is an important hidden danger affecting the safety of water diversion project. In this paper, combined with the actual situation of Central Yunnan Water Diversion Project, the risk assessment system of tunnel collapse is carried out, and the risk assessment system of tunnel collapse containing 11 representative indicators is established. The improved G2 method and entropy weight method are used for subjective and objective weighting, and the moment estimation theory is used for combined weighting. The improved G2-EMW-TOPSIS model is constructed. The model is used to evaluate the collapse risk of Central Yunnan Water Diversion Project and the evaluation grade is obtained. The research shows that the collapse evaluation grades of the four sections of the tunnel are medium risk, and the collapse risk evaluation grades of the five sections are high risk. The evaluation grades of collapse calculated by this model are basically consistent with the actual grades, and the evaluation accuracy is improved from 55.6 % to 88.9 % compared with the cloud model. It can be used for the evaluation and analysis of collapse risk in Central Yunnan Water Diversion Project, and provide theoretical support for the construction and operation of Central Yunnan Water Diversion Project.