The Sanhekou water control project is composed of dam, flood discharge and energy dissipation, water supply system behind dam, connecting tunnel and other projects. The dam is a RCC(Roller Compacted Concrete) double-curved arch dam, which is the second highest domestic RCC arch dam in China. The construction of the dam faces difficulties, including the complex geological and topographic conditions of the project, numerous electrical equipment in different plants, complicated professional cooperation, and large engineering calculation workload. This paper applies the BIM technology to carry out online collaborative design, achieving the design of multi-specialty in same platform through using the geological model, hydraulic model, hydraulic model, electrical equipment model, building structure model and metal structure model. The application of BIM-based technology in the Sanhekou water control project has realized the efficient communication with the owner, and optimized the design scheme. The 3D design results is able to solve the on-site problems, and to facilitate the rapid statistics of the project in the process of engineering. The combination of the CAD (Computer Aided Design) technology and CAE (Computer Aided Engineering) simulation has realized the separation of modeling and calculation, and improved the design efficiency.