Objective：To analyze the expression of Golgi alpha-mannosidase Ⅱ（GMⅡ） in different gastric cancer cell lines and to in－vestigate the role of GMⅡ in gastric cancer genesis. Methods：The pGPU6/GFP/Neo-GMⅡ-1406 gene was transfected into MGC-803 and SGC-7901 cells using cationic liposome assay. Rates of transfected positive cells were observed and calculated under invert microscope. Gene and protein expression of GMⅡ，E-cadherin and α-catenin were tested using RT-PCR and Western blot respec－tively. Invasive abilities of cancer cells were analyzed by cell scratch and Transwell assay. Results：Protein expression of GMⅡ was significantly inhibited and expression of E-cadherin and α-catenin in MGC-803 and SGC-7901 cells was up-regulated compared with those of untransfected cells（P＜0.05）. Cell scratch assay showed that the invasive abilities of cells transfected with GMⅡ gene were weaker than those of control group cells（P＜0.05）. Transwell invasive assay demonstrated that the invasive abilities of cells trans－fected with GMⅡ gene were weaker than those of shNC groups. Numbers of Transwell cells were 65±5，197±6，186±5，72±4，178±4，184±5 in three groups during 18 h，with statistical differences（P＜0.05）. Conclusion：GMⅡ gene silencing contributes to decreased invasive ability of gastric cancer cell lines，which is involved with up-regulation of E-cadherin and α-catenin expression.