The present invention relates to a highly efficient antiangiogenesis agent, which is a polypeptide for inhibition of angiogenesis Ile-Val-Arg-Arg-Ala-Asp-Arg-Ala-Ala-Val-Pro, connected with a polypeptide containing Arg-Gly-Asp on its one end or two ends. The inhibiting agent can be synthesized or gene engineered. The invention also relates to a physiochemical method for modifying the antiangiogenesis agent. Polypeptides with weight percentage of 1-70% preferably about 20-50% are mixed with 20%-95% polyethylene glycol, or heparin, or dextran, or polyvinylpyrrolidone, or polyethylene glycol - poly-amino acid copolymer, or palmitic acid or poly-sialic acid or liposomes solutions； preferably about 50-93% of the above modified substances are fully mixed even and shaken at a shaker at 4°C -40°C, preferably 25°C -37°C for more than 10 min, and the modified substances are separated through appropriate methods. The invention still relates to the use of the above polypeptides and the polypeptide modified substances for manufacturing medicaments for treating human solid tumors.
