The invention provides yak milk formula milk powder for middle and old age, and a preparation method thereof, wherein the main raw materials of the yak milk formula milk powder for middle and old age of per ton comprise: 100-800Kg of yak milk, 2000-4000Kg of fresh milk, 200-475Kg of whey powder (D90), 20-100Kg of whey protein concentrate (WPC34), 10-100Kg of refined plant oil, 15-150Kg of lactose, fructo-oligose, galactooligosaccharide, conjugated linoleic acid, phosphatidylserine, docosahexenoic acid, etc. The formula milk powder uses yak milk and fresh milk as milk raw materials, avoids the need of supplementing a lot of chemically synthesized organic and inorganic nutrients when common milk is individually used, can be better absorbed and metabolized for a consumer, reduces stimulation to gastrointestinal tracts, can enhance antioxidation and immunization capability of the body, promotes oxidation and decomposition of fat, promotes human protein synthesis, regulates balance of various beneficial bacteria, and prevents diarrhoea and constipation.