The invention discloses a preparation method of millet flour according to a quinquagenarian nutrition formulation, and belongs to the technical field of food processing. The method comprises the following steps: (1) mixing materials including millet, hominy chops, buckwheat and oat according to a weight ratio of 5:3:2.5:2.5 to obtain mixed raw materials, washing, adding the raw materials in water with the volume being 3-4 times that of the raw materials, heating to 70-75 DEG C, performing heat preservation for 20-30min, performing jordaning, and filling to obtain filter liquor; (2) adding diastasum diastace in the filter liquor for enzymolysis to obtain an enzymolysis liquor; (3) adding auxiliary materials in the enzymolysis liquor, wherein the auxiliary materials comprise 15-20% of vegetable oil, 20-30% of soy isolate protein, 6-10% of inulin, and 4-6% of isomaltose hypgather by weight based on the weight of the millet to obtain a mixed liquor; and (4) homogenizing the mixed liquor, wherein the first-level homogenizing pressure is 10-20MPa, and the second-level homogenizing pressure is 5-10MPa; and then drying to obtain the finished product. The raw materials are wide in resource, the preparation method is simple, the cost is low, and the millet flour is particularly suitable for enhancing the immunity and building bodies of quinquagenarian.