The invention relates to rice milk and a preparation method thereof, belonging to the field of functional health-care food. The rice milk comprises the following main components in parts by weight: 1-20 parts of rice powder, 0-10 parts of sugar, 0.1-10 parts of concentrated whey protein or/and soy isolate protein, 0-2 parts of inulin, 0.1-0.5 part of glycerin monostearate, 0.1-2 parts of plant oil, and 100 parts of water; and the rice milk further comprises vitamin and a mineral nutrition enhancer. The preparation method comprises the following steps of preparing rice as the main raw material into rice slurry or rice powder dispersion liquid, adding other components, and grinding, homogenizing, heating and quickly cooling. The rice milk disclosed by the invention adopts a novel form, and is convenient to carry, simple and convenient to eat, abundant in nutritional substance, high in protein content, low in fat content, smooth, fine, good in mouth feel, refreshing in fragrance and the like. According to the preparation method, the operation is simple, the cost is low and no pollution exists, and the method is provided for producing steady and uniform rice milk.