The invention relates to the technical field of raw material preparation, and discloses a preparation method of functional raw materials of black whole grains. Comprising the following steps: S1, size mixing; s2, carrying out enzyme passivation; s3, gelatinization is carried out; s4, performing enzymolysis; s5, enzyme deactivation and impurity removal; according to the invention, a grain cold processing method is explored, and an ultrasonic and ultrahigh pressure assisted composite enzymolysis technology is created, so that cold processing of black grains is realized, and a series of low-temperature treatment methods including short-time ultrasonic treatment, ultrahigh pressure treatment, pullulanase, alpha-amylase and alpha-1, 3, 4-trimethyl-1, 3, 4-trimethyl-1, 3, 4-trimethyl-1, 3, 4-trimethyl-1, 3, 4-trimethyl-1, 3, 4-trimethyl-1, 3-trimethyl-1, according to the present invention, the black cereals are processed by using the 1, 4-glucose hydrolase, such that the cold processing of the cereals is successfully achieved, the efficiency is high, the energy consumption is low, the enrichment of the functional active substances in the black cereals is successfully achieved, the anthocyanin retention rate is more than 95%, the resistant starch content is increased by 5-20%, and the total antioxidant activity is increased by 20-130%. The health functions of the black cereals, such as oxidation resistance, aging resistance and bowel relaxing, are remarkably enhanced.