The invention relates to the field of yeast polypeptide, and in particular relates to yeast polypeptide as well as a preparation method and applications of the yeast polypeptide. The preparation method of the yeast polypeptide comprises the following steps: (1) extracting yeast protein in a raw material; (2) adding an alkaline protease for enzymolysis, adding a compound protease for enzymolysis, and collecting the supernatant, thus obtaining an enzymolysis product; and (3) carrying out separating, and carrying out decolorizing, thus obtaining the yeast polypeptide. The yeast polypeptide obtained by adopting the preparation method provided by the invention is colorless and tasteless, the content of polypeptide is 80% or above, 85% or above of polypeptide has the molecular weight being 2000or below, the yeast polypeptide nearly contains no free amino acid, has no bitterness of the common peptide products such as soybean peptide, can be used for food and health products, and can be usedfor improving the flavor of foods, and assisting rehabilitation of physical power after sports. In addition, the obtained yeast polypeptide is excellent cosmetic essence if not being subjected to drying powder-spraying, has the activities of nourishing the skin and resisting wrinkles, can be applied to cosmetics without influencing the color, aroma and the like of the cosmetics, and has the anti-aging efficacy.