A polypeptide, a DNA molecule encoding the polypeptide, a vector, a preparation method and a use therefor are disclosed. The polypeptide comprises an amino acid sequence represented by formula (I) or formula (II): formula (I) comprises an amino acid sequence represented by SEQ ID NO: 1; formula (II) comprises an amino acid sequence obtained by subjecting the amino acid sequence represented by SEQ ID NO: 1 to modification, substituted, and deletion or addition of one or more amino acids. The polypeptide may be used in the preparation of drugs that treat or prevent diseases related to infections caused by bacteria, and can also be used in the preparation of drugs that promote tissue repair and wound healing.