The invention relates to the field of medicines, specifically to an integrin blocker which inhibits generation of tumor vasculature and has integrin endophilicity and binding capacity. The blocker is a polypeptide. The integrin blocker polypeptide can be used to treat solid tumor. The integrin blocker can be applied in the preparation of medicines for treating tumor. The sequence of the integrin blocker is Ala-Cys-Asp-Cys-Arg-Gly-Asp-Cys-Phe-Cys-Gly-Gly-Gly-Gly-Ile-Val-Arg-Arg-Ala-Asp-Arg-Ala-Ala-Val-Pro (the sequence contains two disulfide bonds and the pairing manner is 1-4 and 2-3). The invention is characterized in that the tumor origins from primary or secondary cancer and sarcoma of human head and neck, brain, thyroid, pancreas, lung, liver, oesophagus, stomach, mammary gland, kidney, gallbladder, colon or rectum, ovary, uterus, cervix, prostate, bladder and testis. According to the invention, treatment spectrum of the integrin blocker is greatly expanded, novel thinking and prospect are provided for drug development, and the integrin blocker polypeptide AP25 has substantial social value and market value.