Abstract: Objective To evaluate the effect of overexpression of aldehyde dehydrogenases 1A1（ALDH1A1）on the proliferation，clone formation and invasion of human gastric cancer cell.Methods The eukaryotic expression vector，pEGFP-N1-ALDH1A1，was transfected into gastric cancer cell line MKN-28（experimental group）. The empty vector group（MKN-28 cells transfected with empty vector pEGFPN1）and blank control group（MKN-28 cells without any treatment）were also prepared. The methyl thiazolyl tetrazolium（MTT），clone formation assay and Transwell chamber invasion assay were used to evaluate the cell proliferation，clone formation and invasion ability at 96 h after transfection，respectively. Results The proliferation inhibition rate of experimental group was（19.26±2.01）％，lower than that in empty vector group and blank control group. While the clone formation rate and number of cells penetrating membrane were（25.44±1.74）％ and 219.78±12.93，higher than those in the empty vector group and blank control group（P＜0.05）. No significant difference was observed on the above items between blank control group and empty vector group（P＞0.05）. Conclusion Overexpression of ALDH1A1 can increase the proliferation，colony formation and invasion ability of human gastric cancer cell MKN-28.ALDH1A1 may be involved in the occurence and development of gastric cancer.