The invention discloses a preparation method of instant buckwheat peanut milk powder. The method comprises the following steps of: firstly, screening, cleaning, drying, crushing, curing, digesting, filtering and concentrating to obtain a buckwheat extracting solution; finely selecting, germinating, pulping, boiling and filtering the buckwheat to buckwheat bud pulp which is high in the content of nutrition and health care functional components; carrying out screening, parching and enhancing fragrance, soaking in hot water, grinding pulp, and filtering on the peanut to obtain peanut milk; and mixing the buckwheat extracting solution, the buckwheat bud pulp and the peanut milk, adding cane sugar, mixing sodium carboxymethylcellulose, sucrose fatty acid ester and milk liquid, homogenizing, carrying out freeze drying, and packing. The instant buckwheat peanut milk tea prepared by the method is good in solubleness, savoury, mellow and tasty, exquisite in taste, abundant in nutrition, and enriched in various health care function components, i.e. bioflavonoid, D-chiro-inositol and the like.