The invention relates to the protein field, in particular to a peptide and application thereof. According to the invention, tripeptide Arg-Arg-Tyr acts on human skin fibroblasts to perform CCK-8 proliferation assay, cell proliferation detection assay by Edu process, and cell cycle detection assay by flow cytometry on human skin fibroblasts. The assays prove that the tripeptide Arg-Arg-Tyr can effectively promote the proliferation of human skin fibroblasts and increase the proportion of S+G2M phase, has definite therapeutic effect on prevention or treatment of skin aging, and has small side effect, thus having important practical significance.