The invention relates to an amino acid bound with polyethylene glycol with the following general structure: R-PEG-CO-X-amino acid or R-PEG-X-amino acid; wherein, PEG represents for polyethylene glycol chain; R represents for a hydroxyl group or an oxyl; the oxyl can be chosen from the C1 to C12 alkoxy, cycloalkoxy or aralkoxy; wherein, X represents for the heteroatom with active hydrogen removed except Alpha-carboxyl and Alpha-amino group in amino acid. Utilizing the amino acid bound with polyethylene glycol to synthesis polypeptide, the polypeptide is made from polypeptide positioned on specific position, not only improving the pharmacokinetics, but also having no effect of original treatment. The invention discloses the production method for the amino acid bound with polyethylene glycol.