Aimed at the outstanding contradiction issue between supply and demand of water resources in condition of drought in the large irrigation area of Qingling river, the article established the optimal operation model of irrigation reservoir by use of the data of runoff, irrigation area water and reservoir. The result showed that the total water diversion is 6.6825 million m3 under condition of guaranteed frequency of 75%, the water diversion from Hujiashan reservoir is the maximum, and that from Dakanglang is the minimum.