Objective To study effect of carcinoembryonic antigen (CEA) positive targeted lymphocytes on gastric cancer cells in vitro and in vivo. Methods The peripheral blood mononuclear cells (PBMCs) were isolated from the peripheral blood of healthy volunteers. The recombinant vector anti-CEA-scFv-CD3ζ-pcDNA3.0 was transfected into the PBMCs by lipofectamine 2000, by this means, the CEA special lymphocytes were obtained. Meanwhile, the PBMCs transfected with empty plasmid pcDNA3.0 were used as control (empty vector lymphocytes). The different lymphocytes and gastric cancer cells (CEA positive KATOⅢ gastric cancer cells and CEA negative BGC-823 gastric cancer cells) were co-cultured, then the ability to identify the gastric cancer cells and it’s effect on apoptosis of gastric cancer cells were observed at 24 h or 36 h later respectively. The CEA special lymphocytes and empty vector lymphocytes were injected by the tail vein of nude mice bearing gastric cancer cells, then it’s effect on the tumor was observed. Results ① The CEA special lymphocytes could strongly identify the KATOⅢ gastric cancer cells (identification rate was 72.3%), which could weakly identify the BGC-823 gastric cancer cells (identification rate was 7.8%). ② The apoptosis rate of the co-culture of CEA special lymphocytes and KATOⅢ gastric cancer cells was significantly higher than that of the co-culture of empty vector lymphocytes and KATOⅢ gastric cancer cells (P=0.032), which had no significant difference between the co-culture of CEA special lymphocytes and BGC-823 gastric cancer cells and the co-culture of empty vector lymphocytes and BGC-823 gastric cancer cells (P=0.118). ③ The tumor volume of the co-culture of CEA special lymphocytes and KATOⅢ gastric cancer cells was significantly smaller than that of the co-culture of empty vector lymphocytes and KATOⅢ gastric cancer cells (F=5.010, P<0.01) or the co-culture of CEA special lymphocytes and BGC-823 gastric cancer cells (F=4.982, P<0.01), which had no significant difference between the co-culture of CEA special lymphocytes and BGC-823 gastric cancer cells and the co-culture of empty vector lymphocytes and BGC-823 gastric cancer cells (F=1.210, P>0.05). Conclusion CEA special lymphocytes can promote cell apoptosis and inhabit tumor reproduction of CEA positive gastric cancer cells in vitro and in vivo.