By establishing ten risk evaluation indices for an international BOT hydropower project, the weight of each index is quantitatively determined by using the entropy method. Based on the TOPSIS method, the positive and negative degrees of association from each project to the ideal solution are investigated and integrated. Thus a decision model of grey correlation method based on the entropy and TOPSIS is established to evaluate the investment risk of the international BOT hydropower project. Five typical international BOT projects are selected to make empirical analysis. The results show that the risks of international BOT hydropower projects can be analyzed by the proposed method effectively and objectively. The geological disaster risk, land acquisition risk, construction risk and economy and contract risk of international BOT hydropower projects have larger weights, while the government credit risk and infrastructure project risk have less effect owing to the relatively backward areas. Finally, the investment risks of five projects are analyzed and sorted by using the grey correlation decision model.