For the reservoirs used to regulate local surface water resources, new dispatching rules need to be formulated due to the influence of multiple water sources to improve the water resource utilization efficiency. Considering the low regulation and storage capacity of unconventional water, water transfer and supply rules are set for the reservoirs in the water receiving area on the basis of priority allocation of unconventional water, and the reservoir optimal operation model considering the efficiency of water transfer and supply is established. The ideal point method and genetic algorithm are used to optimize the operation rules. Taking the Mishan Reservoir in Weihai City as an example, the results show that compared with the standard operation strategy, the optimized reservoir operation rules reduce the average annual water transfer by 26.924 million m³ and the annual average waste water by 4.175 million m³. The utilization ratio of natural incoming water and external transferred water is improved. The dependence of external water transfer in dry years is higher than that in wet years and normal years, and the average water transfer volume is only reduced by 3.98 million m³. Under this regulation, the assurance rate of agricultural water supply can be increased from 75% to 88.4% by reducing the amount of external water transfer and increasing the allocation of unconventional water.