Objective:To investigate the influence on the growth and metastasis of gastric cancer by transfection of B7-1. Methods: Plasmids B7-1pcDNA3.1(+) and pcDNA3.1(+) were transfected into SGC-7901,then selected by G418 to establish the stable cell lines S-B and S-P. The expression of B7-1 mRNA and protein was detected, and then the distribution of cell cycle and the proliferation index(PI) was tested. Human peripheral blood mononuclear cells(PBMC) were separated and co-cultured with gastric cancer cell lines whose adhesion and cytotoxicity were tested Apoptosis condition of gastric cancer cells were also monitored. Gastric cancer cells were inoculated into the great curve of BALB/c nude mouse close to the gastric antrum Growth and metastasis of the gastric cancer were observed. Results:B7-1 was high expressed in S-B, but wasn’t expressed in S-P and S. S-B,S-P and S didn’t have significant difference in proliferation index. Adhesion and cytotoxicity of PBMC to S-B were stronger than that of S-P and S, but no significant difference between S-P and S. Tumorigenesis and lymph node metastasis of S-B were both lower than that of S-P and S. Lymphocytes were intensively infiltrated in both the S-B tumors and its metastatic lesions, however, were scarcely observed in the lesions associated with S-P and S. Conclusion:The transfection of B7-1 enhanced the immunogenicity of gastric cancer cell and inhibited its growth and lymph node metastasis.