A method for moisturizing skin using P-113 peptide, which comprises administering to the skin of a subject a composition containing a P-113 peptide, wherein the P-113 peptide comprises the sequence of SEQ ID NO: 1. P-113 peptide is hypoallergenic and non-cytotoxic, which means it does not cause harms or allergies to the skin and can be used as an ingredient of cosmetic products. The P-113 peptide fragment has moisture absorption and moisture retention effects, therefore it can be formulated with other ingredients of moisturizing cosmetic products, enhancing the moisturizing effect of other moisturizing ingredients. In addition, the P-113 peptide fragment is capable of inhibiting the production of MMP-9 and thus decreases collagen degradation, thereby achieving the anti-wrinkle and anti-aging effects. The cosmetic disclosed herein comprises not only the peptide, but also active ingredients of cosmetic products and essence liquid formulations.