Abstract: Objective: To explore the suppressive effects of snake venom cystatin gene(sv-cystatin) on metastatic potential of human gastric carcinoma cell line SGC-7901. Methods: A 297bp DNA fragment ecoding sv-cystatin was designed based on the biased codon usage of yeast. Four partial overlapping cystatin geng fragments were synthesized, and the full length of sv-cystatin cDNA was obtained and linked to pUC18 vector. Expression plasmid pcDNA3.1/sv-cystatin was constructed and transfected into gastric carcinomar cell line SGC-7901 using lipofectamine gene transfer technique. Sv-cystatin gene expression was detected in SGC/sv-cystatin cells by RT-PCR, Western blot assay. Cell-matrix adhesion assay was used to study the adhensive ability of SGC/sv-cystatin cells. The effect of sv-cystatin expression on the invasion and migration of SGC7901 cells was investigated by transwell chamber system. Results: Expression of sv-cystatin was detected after cystatin gene-transfection in SGC/sv-cystatin cells. Matrigel invasion and migration assay showed that the invasion and migration of SGC/sv-cystatin cells were less than those in control groups, sv-cystatin. However, it did not affect the adhesive ability of SGC7901 cells with the matrix. Conclusion: The expression of sv-cystatin could inhibit SGC-7901 cells invision and migration in vitro. It suggests that sv-cystatin may have some role in reduction of gastric carcinoma cell invasion.