Abstract: To maximize the benefits of water diversion and regional water resources, reservoir joint operation has become a key method for improving system efficiency. This paper describes a case study of the Tiegang-Shiyan multi-reservoirs in the water diversion and supply system for the west of Shenzhen. First, we analyzed the operation policies for common water users (i.e. several reservoirs supply water to the same users) and the pumping station of the system. The operation policies for common water users were formulated based on two methods. One adds an operation line on the operation chart of the main supply reservoir; the other constructs an equivalent aggregated reservoir by which the operation policies are worked out. The operation policies for the pumping station were formulated by setting a pumping line and a limit line on the operation chart of the multi-reservoirs. Then, the total volume of water supply by the multi-reservoirs to common water users was examined using four schemes. For each of the schemes, a progressive optimality algorithm (POA) was used to optimize its parameters of operation policies. Finally, using the operation policies already determined, we simulated the water supply and diversion operation in the four schemes, and evaluated and compared their efficiencies and benefits.