The aim of this study was to investigate the mechanisms of mono-functional alkylating agent MNNG to damage human gastric epithelial GES-1 cells and roles of Wnt/β-catenin signaling pathway in the process. The GES-1 cells were treated with MNNG (2 × 10-5 mol/L) for 24 h. The morphological changes of the GES-1 cells were observed under inverted microscope 2 d after treatment. The cell viability was measured by MTT assay. The apoptosis and cell cycle distribution of the GES-1 cells were analyzed by flow cytometry. The mRNA expressions of β-catenin, GSK-3β, c-Met and MMP7 in the GES-1 cells were detected by qPCR. The protein expressions of β-catenin, GSK-3β, p-GSK-3β and c-Met were determined by Western blot. The results showed that MNNG induced the injury of GES-1 cells and changed the normal cell morphology to irregular long spindle shape. MNNG induced the apoptosis of GES-1 cells and blocked the cell cycle progression obviously. MNNG up-regulated the mRNA expressions of β-catenin, GSK-3β, c-Met and MMP7, and increased the protein expressions of β-catenin, GSK-3β and p-GSK-3β. These results suggest that the damage of GES-1 cells induced by MNNG may be related to the activation of Wnt/β-catenin signaling pathway, which will provide the basis for the study of cell model of gastric mucosal cell injury.