The invention discloses a marine compound protein powder containing oyster peptide and a preparation method of the marine compound protein powder containing the oyster peptide. The marine compound protein powder is prepared from, by weight, 60-80 parts of soybean protein isolate, 8-20 parts of whey protein, 2-5 parts of peanut protein, 1-5 parts of the oyster peptide, 3-6 parts of maltodextrin, 0.3-0.6 part of soyabean lecithin, 0.3-0.7 part of silicon dioxide, 0-16 parts of fructo-oligosaccharide, 0-1.2 parts of L-calcium lactate, 0-0.05 part of zinc lactate and 0-0.15 part of taurine. The preparation method includes: weighing all components according to the parts by weight, well mixing in an automatic mixer, feeding into a fluidized bed to realize granulation, sterilizing and subpackaging. The marine compound protein powder contains marine oyster peptide and is technically simple in preparation and easy for industrialization, and amino acid composition of the marine compound protein powder is superior to an estimated value, recommended by the Food and Agriculture Organization and the World Health Organization, of physiological requirement on essential amino acids.