Abstract: A GIS-based approach is presented to visualize the complex space-time relationship among all aspects of the construction diversion of hydroelectric project. The dynamic 3D digital model of construction diversion is built. Then depending on this model, the functions of dynamic display, spatial analysis and interactive operations are developed, and dynamic simulation for the full process of construction diversion is realized. It gives the designers and decision-makers a scientific and effective tool to analyze the design and support decision-making. An example of engineering application is given to show the effectiveness and practicability of this approach.