The invention discloses a summer flower composite duck feed and a preparation method thereof. The duck feed comprises the following raw materials: 32-35 parts of corn, 13-18 parts of bean cake, 15-20 parts of broken rice, 0.3-0.5 part of lysine, 0.35-0.55 part of methionine, 1-2 parts of shell powder, 3-5 parts of calcium hydrogen phosphate, 0.4-0.6 part of salt, 0.5-0.7 part of premix, 3-4 parts of black fungus, 0.08-0.12 part of radix rehmanniae recen, 0.1-0.3 part of bashen, 1-2 parts of willow leaves, 0.3-0.5 part of Tropaeolum majus, 0.3-0.5 part of radix bupleuri, 2-4 parts of cassia seed, 2-4 parts of lotus, 0.8-1.2 parts of lily flower, 0.5-0.7 part of impatiens balsamina and 0.4-0.6 part of melon vine. The formulation provided by the invention has the advantages of low cost, easily available ingredients and easy preparation method; the feed is added with traditional Chinese medicines including radix rehmanniae recen, bashen, Tropaeolum majus, radix bupleuri and semen cassiae seed, effectively regulates temperature of the duck body and prevents heatstroke of duck; the feed is also added with black fungus, willow leaves, lotus, lily flowers, impatiens balsamina and melon vine; therefore, the feed is rich in nutrition and low-cost, has obvious fattening effect, realizes low illness rate, and effectively overcomes lack of nutrients.