Abstract: The small molecule cyclic peptides containing RGD (Arg- Gly- Asp) motif is the interacting site between integrin and its ligand. These peptides can mediate cell- cell and cell- extra- cellular matrix interactions. The alpha beta 3 integrin is highly restricted, with expression on cells surface of many malignant tumors and on the neovasculature endothelial cell, but has no expression or cannot bedetected in normal organic system. The alpha beta 3 integrin is the new target of tumor therapy and the research on RGD in the field of tumor therapy has become a hot spot. The radiolabeled RGD-pep-tides can be used as a potent tumor ima ng reagent. Additional RGD- peptides can induce apoptosis of tumor cells and as a vector, it can play a very important role in targeting therapy of cancer.