The invention discloses purple-potato-containing nutritional rice and a preparation method. The nutritional rice is prepared from whole purple potato powder, starch, isolated soy protein, gel, composite vitamin enhancer, composite mineral enhancer and water in a ratio. The method comprises the following steps of: A, selection and treatment of raw materials; B, mixing and stirring: stirring and mixing the isolated soy protein, the gel and the enhancers uniformly, adding the starch, mixing, then adding the whole purple potato powder, stirring and mixing, and adding water; C, extrusion forming: after the raw materials are mixed and stirred uniformly, adding the mixture into an extruder through a feeder, cutting the extruded mixture into rice grains at the tail end of the extruder after the extruded mixture passes through a rice grain template, cooling, screening with a vibrator, separating out dregs, collecting and drying; D, water controlled drying: drying the extruded rice grains in hot air to improve the storage performance; and E, packing: cooling the rice grains to room temperature, quickly and quantitatively filling and sealing. The nutritional rice has reasonable formula, good nutrition, low cost, no pollution and high nutritional value. The method is simple and convenient to operate, and is suitable for large scale and industrialized production of purple potatoes.