The invention discloses a mixed feed for treating cow hypogalactia and a preparation method thereof. The feed comprises the following raw materials: alfalfa hay, straws, corn stalks, rice bran, soybean meal, cottonseed meal, corns, millets, wheat bran, sticky rice, DDGS rapeseed meal, green soybean meal, carrots, yam powder, corn oil, salt, a vitamin premix and a trace element premix. The preparation method comprises the steps of crushing, dosing and granulating. The mixed feed and the preparation method thereof provided by the invention have the beneficial effects that the pharmaceutical composition has the main functions of tonifying spleen and regulating qi, and auxiliary functions of benefiting qi and nourishing blood, the immunity of cow is improved, the lactation yield, butter-fat percentage, milk protein, lactose and dry substances in milk can be improved, breast plump and normal development of nipples are promoted, the milk is full, and the phenomena of rapid appetite reduction or no eating do not occur; the mixed feed also has the advantages of low toxic side effects and significant efficacy, and well ensures the normal growth of breasts and other body organs.