We used the intein mediated protein intramolecular transsplicing to cyclize poly GRGDSPA peptide, to investigate its antiinvasion and anti-metastatic functions to murine melanoma B16 cells. Conclusion:Genetic engineered cyclic poly GRGDSPA by intein mediated intramolecular protein trans-splicing could efficiently inhibit the invasion and metastasis of cancer cells. In addition, the cyclic poly GRGDSPA showed more efficiently thanlinear poly GRGDSPA in in vivo anti-metastasis. Inhibition of integrin-ECM interaction on the cell surface might be a promising anti-metastasis strategy and intein might be used as a means producing cyclic poly GRGDSPA for augmentation of the antitumor effect.