The invention discloses anti-oxidation multigrain nutritious flour and a preparation method. The anti-oxidation multigrain nutritious flour is prepared from, by mass, 250-300 parts of wheat flour, 50-70 parts of glutinous rice flour, 8-12 parts of black rice flour, 8-12 parts of red date powder, 30-40 parts of soybean protein powder, 30-40 parts of oat meal, 8-12 parts of sesame powder, 15-21 parts of powdered probiotics, 6-10 parts of soybeans, 6-10 parts of mung bean, 6-10 parts of red beans, 10-14 parts of corns, 4-6 parts of sweet potatoes, 3-5 parts of coix seed, 3-5 parts of buckwheat powder, 15-21 parts of whole tartary buckwheat powder, 21-37 parts of nutrient enrichment auxiliary materials, 10-18 parts of traditional Chinese medicine auxiliary materials, 9-15 parts of herbal auxiliary materials, 1.7-3.2 parts of an amino acid mixture and 2-4 parts of a vitamin mixture. The anti-oxidation multigrain nutritious flour has an anti-oxidation function and is capable of improving human immunity and reducing diseases.