Integrin aⅡbb3 of the platelet surfaces regulates the thrombosis formation. aⅡbb3 binds to the RGD sequence (Arg-Gly-Asp) of fibrinogen, promotes the platelet aggregation and finally leads to the thrombus. We obtained the three-dimensional molecular structure of aⅡbb3 using homology-modeling (modeller8v2 software), with integrin avb3 (pdb code 1JV2) as the template. Accordingly, a cyclic RGD(RGD-c) peptide was designed to bind aⅡbb3 as an antagonist and to block the formation of thrombus. We added two amino acids X, Y to both sides of RGD-c. X and Y could bind to each other by disulfide bond that finally made RGD-c a cyclic peptide. The optimum structure of RGD-c was obtained from the energetic optimization processes. All amino acids were placed at the X and Y to conduct Molecular Docking to the integrin aⅡbb3. We got the optimum structure of RGD-c by energetic optimization and the antagonistic combination analysis. The results might provide an insight into designing and screening integrin aⅡbb3 antagonists.