An international hydropower EngineeringProcurementConstruction(EPC)contractordesigner alliance model was established based on literature review to investigatethe cooperation methods between international hydropower engineering enterprises in China. Correlation analysis, hierarchy luster analysis and typical analysis have been adopted to analyze the data collected by questionnaires and interviews. The results addressed the interactions of the alliance factors and the relationships between incentives, alliance, and strategic partnership, which validated the model, and revealed the mechanism of alliance. The results of the survey data analysis demonstrate that: ① joint tendering is the basis for indepth cooperation between the contractor and the designer. After successfully wining the bid, two parties equitably allocate rewards/risks to enhance trust. Based on trust, effective communication is promoted, which enables the efficient circulation of information between the two parties, and thus allow problems encountered in project implementation to be solved in a timely manner. ② Alliances are underpinned by incentives, which promotes the development of partnerships; at the same time, a good partnership facilitates the implementation of incentives. The cooperative partnership between the contractor and the designer established in the implementation of the project lays a good foundation for longterm strategic cooperation. After the successful delivery of the project, the contractor and the designer are driven by incentives to share the project benefits, which helps them to establish a strategic alliance that enables joint tendering for future EPC projects, facilitating the expansion of their share of the international market.