The invention discloses a synthetic polypeptide, the amino acid sequence of the synthetic polypeptide meets the following general formula: Ac-X0-(X1-X2-X3-X4)n-NH2, wherein Ac is an acetylized N-terminal; X0 is an L-amino acid, and the type of the amino acid is Ala, Val or Gly; X1, X2, X3 and X4 are all L-amino acids or D-amino acids, X1 is a positive charge amino acid Arg, Lys or His, X3 is a negative charge amino acid Asp or Glu, and X2 and X4 are amino acids Ala, Val or Gly without charge; X1-X2-X3-X4 is a repeated sequence; and n is repeated times of amino acid arrangement in the sequence, and is equal to 2, 3 and 4. The polypeptide has the characteristics of forming a nano fiber screen through self-assembly, and can form a gel-like fiber screen in the particle environment in vitro or in vivo for hemostasis or wound nursing.