The invention discloses compound protein powder and a preparing method thereof. The compound protein powder comprises soybean protein powder, whey protein powder, highland barley protein powder, potato protein powder, sweet potato protein powder, collagen protein powder, pea protein powder, walnut powder, egg white powder, yolk powder, soybean lecithin, rape pollen, sweetening agents and essence. The preparing method comprises the steps of raw material baking, cooling, mixing and packaging, and finished products are obtained. The raw material ratio accords with the modern health maintenance principle, the formula is scientific and reasonable, the good effect that nutrient needed by a human body is supplemented is achieved, taste is good, and flavor is unique.