Abstract: The diversion tunnels of the Shuibuya Project feature high head, big discharge, long tunnel line and complicated geologic conditions. For solving their hydraulic problems, a model test with a scale of 1∶80 was conducted. The paper summarizes the main results, including discharge capacity and the main factors affecting it, pressure characteristics and its improvement measures, and the comparison of energy dissipation schemes downstream the outlet. The research results offers basic data for optimal design of the diversion tunnels.