The invention discloses a cereal composition with toxin-removing and skin-beautifying effects and a preparation method and an application thereof. The cereal composition consists of the following materials in parts by weight: 5 to 15 part of job's tears, 30 to 50 percent of broomcorn, 30 to 50 percent of black sesame, 18 to 32 parts of pumpkin seed, 30 to 45 parts of purple bean, 10 to 20 parts of liquorice, 20 to 35 parts of oat, 18 to 25 parts of black rice, 10 to 20 parts of cassia seed, 15 to 25 parts of pine pollen, 10 to 20 parts of lily bulb, 5 to 15 parts of horsebean, 15 to 20 parts of hawthorn, 2 to 8 parts of malt, 5 to 10 parts of Chinese yarn, 10 to 15 parts of highland barley, 20 to 30 parts of mung bean, 10 to 20 parts of rice bean, 10 to 15 parts of arabinose, 25 to 35 parts of wheat bran powder, 5 to 10 parts of purple sweet potato, 5 to 10 parts of carrot, 5 to 10 parts of common selfheal spike and 5 to 10 parts of millet. The cereal composition is prepared by preprocessing, heat treatment and grinding processes. Compared with the prior art, the cereal composition adopts a variety of cereals, can play a role of detoxifying and cleaning the internal organs, has a good effect in detoxifying the liver and the gall, relaxing the bowels, purifying blood and removing toxin and beautifying skin, is discovered by verification to have an excellent remarkable effect in detoxification and cleaning, medicine-food homology and internal organ regulation, and is suitable for sub-healthy or sick people to eat for a long term.