Currently, the application efficiency of information technology in EPC projects of hydraulic engineering is low. Applying the building information model(BIM) technology to the EPC projects of hydraulic engineering can promote the sharing of information and knowledge throughout the life cycle of the project, improve the capability of collaborative work between project participants, and achieve added value. Exploring the influencing factors and mechanism for the added value of BIMbased EPC projects of hydraulic engineering is the premise and key to realize the project value. By using the qualitative research methods, interviewing 20 persons engaged in the construction or researches of EPC projects of hydraulic engineering and reviewing 90 related documents, the influencing factors for the added value of BIM-based EPC projects of hydraulic engineering are identified. The DEMATEL-ISM method is used to analyze the correlation between the factors, and a hierarchical structure of the influencing factors is established. The results show that the market demand for BIM is the root influencing factor, and the technical support capability of BIM, enterprise attention and investment level and management organization are the core factors for the added value of BIM-based EPC projects of hydraulic engineering.