The invention discloses a composite rice milk drink and a preparation method thereof. The product of composite rice milk is prepared by the steps of material selection, peanut baking, pulp grinding, rice cleaning and soaking before pulping, gelatinization, mild enzymolysis, blending, homogenizing, filling, sealing, sterilizing, cooling and packaging. In the invention, the rice-peanut composite rice milk is prepared by combining the biological enzymolysis technology with the high-pressure homogenizing technology, the starch is partially hydrolyzed, the grease in peanut and rice starch form a stable emulsified state of semi-water in oil and semi-oil in water, and the recrystallization of the rice starch in a storage process of rice milk drink is effectively prevented so as to prevent the retrogradation of rice milk drink and prolong the shelf life of the rice milk drink. The rice milk drink disclosed by the invention integrates the nutritional ingredients of rice and peanut, and the mouthfeel, flavor and nutritional value of the product are increased; and the preparation method is simple and easy to implement, adopts general equipment, has strong operability, can effectively solve the problem of retrogradation deposition of rice milk, and is suitable for industrial large-scale production of rice milk drink.