The invention provides black fungus and buckwheat nutritional rice Krispies which is prepared by steps of pretreatment, fermentation, after-ripening, embryo preparation, extrusion, cutting, drying, microwave puffing, baking and cooling preparation. Ingredients of the nutritional rice Krispies are selected from the following raw materials: raw materials include black fungus, cooked bucket wheat flour and potato starch; and auxiliary materials include one component or a mixture selected from yolk powder, food additives, plant oil, tomato powder, spice, edible salt and drinking water. By the above technical scheme, the product has the best organoleptic quality, is exquisite and crispy in taste, has rich fragrance of buckwheat and slight fragrance of edible fungus, has high nutritive value, is easy to digest and absorb, is beneficial to iron supplementation, blood-nourishing and youthful looks retaining, is an ideal nutritional snack food, and has good social benefit and economic benefit. In addition, the invention also discloses a preparation method of the black fungus and buckwheat nutritional rice Krispies.