The invention discloses a prescription milk powder for a piglet and a preparation method thereof. The prescription milk powder comprises the following components: whole milk powder, desalinized whey powder, whey concentrated protein, egg powder, swollen rice powder, powdered grease, glucose, lactose, lysine, methionine, threonine, trace element additive, complex vitamin, glutamine, choline chloride, vitamin C, milk flavouring agent, calcium lactate, calcium dihydrogen phosphate, antioxidant, astragalus polysaccharide and oligosaccharide. The piglet prescription milk powder has high palatability and high water solubility, is abundant in immune globulin, immune polysaccharide, functional oligosaccharide and high-cream lactoprotein, can well overcome the defect of insufficient milk absorption of the piglet, improves the immunity and disease resistance of the piglet and the raising rate and uniformity before ablactation and during the care period, and fully develops the growth potential of the piglet.