Purpose To investigate the expression of C1GALT1 in gastric cancer and its effect on the biological be-havior of BGC-823 in gastric cancer cells.Methods The ex-pression of C1GALT1 mRNA and protein in gastric cancer tis-sues and normal gastric mucosa,gastric cancer cells and normal gastric mucosal cells was analyzed by bioinformatics,qRT-PCR and Western blot;the transient transfection of siRNA into BGC-823 cells was designed with C1GALT1 cDNA sequence as the target.Transwell assay was used to detect the effect of C1GALT1-siRNA on the migration and invasion ability of BGC-823 cells in gastric cancer.Western blot method detected the expression of epithelial-mesenchymal transition(EMT)-related proteins in BGC-823 after transfection of C1GALT1-siRNA.Re-sults C1GALT1 was highly expressed in gastric cancer tissues and cell lines BGC-823,SGC-7901 and MGC-803,and the ex-pression levels were positively correlated with gastric cancer pathological stages Ⅰ and Ⅱ(P＜0.05).After interfering with C1GALT1 in BGC-823 cells,the ability of migration and inva-sion decreased(P＜0.05),epithelial cell markers E-cadherin and Claudin-1 protein expression increased,while mesenchymal cell markers vimentin and Slug protein expression decreased(P＜0.05).Conclusion C1GALT1 is highly expressed in gastric cancer tissues and cells,silencing of C1GALT1 can inhibit mi-gration and invasion ability of gastric cancer,the mechanism may be related to EMT.