The invention relates to soybean whey protein composite powder and a preparation method thereof. The soybean whey protein composite powder comprises, by weight, 5-10 parts of soy isolate protein powder, 12-20 parts of whey protein concentrate powder, 3-10 parts of fish collagen protein powder and 0.5-2 parts of taurine. In preparation, the soy isolate protein powder, whey protein concentrate powder and fish collagen protein powder are mixed according to the weight part ratio, other components are added into the mixture through a fluidized bed, the mixture is subjected to granulation, and the product is collected and is sterilized so that a finished product is obtained. Compared with the prior art, the preparation method utilizes soy isolate protein powder, whey protein concentrate powder and fish collagen protein powder as main raw material and uses taurine, coix seed powder, poria cocos powder, soya bean lecithin and soybean oligosaccharides so that the soybean whey protein composite powder is rich in comprehensive and balanced nutrients, has high protein content, is pure natural, does not produce pollution, does not contain a preservative, contains multiple natural active components, has low cholesterol content, low fat content and low heat and fast supplies comprehensive nutrients.