Abstract: Objective To study the effect of glucosaminyl （N-acetyl） transferase 3 （GCNT3） on the proliferation,apoptosis,invasion and epithelial mesenchymal transition （EMT） of lung adenocarcinoma cells. Methods Lung adenocarcinoma and matched paracancerous tissue specimens were collected from 30 lung adenocarcinoma patients undergoing surgical resection in Punan Branch of Renji Hospital,Shanghai Jiao Tong University School of Medicine from 2020 to 2023. The expression level of GCNT3 in lung adenocarcinoma and paracancerous tissues was detected using RT-qPCR. Human lung adenocarcinoma H1650 cells were cultured in vitro,and transfected with GCNT3 small interfering RNA （Sh GCNT3 group） and Lipofectamine 2000 （NC group）. The relative expression level of GCNT3 mRNA was detected by RT-qPCR. The proliferation viability of cells in the NC and Sh GCNT3 groups was assessed by CCK-8 assay. The effect of GCNT3 on the apoptosis of H1650 cells was analyzed using flow cytometry. The effect of GCNT3 on the invasion ability of H1650 cells was detected by Transwell assay. The effect of GCNT3 on the changes in the expression levels of EMT-related proteins in H1650 cells was determined by Western blot. Results The relative expression level of GCNT3 mRNA in lung adenocarcinoma tissues was significantly higher compared with that in paracancerous tissues （P < 0.05）. Compared with the NC group,the relative expression level of GCNT3 mRNA was down-regulated,the proliferation rate of cells was significantly reduced,the cell invasion ability was weakened,the EMT phenotype was inhibited,and the apoptosis rate was significantly increased in the Sh GCNT3 group （all P < 0.05）. Conclusion GCNT3 gene promotes the proliferation,invasion and EMT of lung adenocarcinoma cells and inhibits cell apoptosis.