The invention discloses an edible grain, bean and potato coarse cereal rice composition and a preparing method thereof and belongs to the technical field of grain deep processing. According to the edible grain, bean and potato coarse cereal rice composition, broken rice is used as a main raw material, after ultrasonic cleaning, microwave curing, drying and sterilizing of the broken rice, the broken rice, grain powder with a special flavor, enzymatic hydrolysate and other functional raw materials are pelletized, and then grain arrangement and processing through a microwave drying device are carried out, so that the edible grain, bean and potato coarse cereal rice composition is obtained. The edible grain, bean and potato coarse cereal rice composition has a tissue structure, granularity, hardness and viscosity which are similar to those of rice, can be boiled and cooked with rice, has the taste and chewiness, which are similar to those of cooked rice, is unique in flavor, soft in fragrance, high in appetite attractiveness, easy to digest and comprehensive in nutrition, and can improve the immunity and disease resistance of the human bodies and improve the gastrointestinal function. The guarantee period is three times of that of commercial rice. More importantly, a shortcut is developed for the efficient value-added comprehensive utilization of the broken rice, the road for the deep processing of the broken rice is broadened, and the economical value of the broken rice is increased. Better social benefits and economic benefits are realized and a sustainable development road for the deep processing of agricultural byproducts and the effective solving of Three-Rural problems is explored.