Objective To construct a human breast epithelial MCF-10A cell model overexpressing Armcx3 and explore its effects on proliferation, migration and invasion of MCF-10A cells. Methods The expression of Armcx3 in breast cancer and normal tissues was analyzed by bioinformatics. Control lentivirus and Armcx3 lentivirus were infected with MCF-10A cells and screened with purinoxin. The experimental cells were divided into three groups: blank control group, overexpressed control group and overexpressed Armcx3 group. Western blot analysis was performed to detect the expression of Armcx3 protein and EMT-related protein in cells of each group. CCK-8 assay was used to detect cell proliferation, scratch assay and Transwell migration assay were used to detect cell migration. Results The expression of Armcx3 mRNA and protein in breast cancer was significantly higher than that in normal tissues (P<0.0001). The MCF-10A cell model overexpressing Armcx3 was successfully constructed. The results of CCK-8 experiment showed that the proliferation ability of MCF-10A cells in the overexpressed Armcx3 group was significantly increased compared with the blank control group and the overexpressed control group (P<0.001). The results of scratch test and Transwell migration test showed that the migration ability of MCF-10A cells in the overexpressed Armcx3 group was significantly enhanced compared with the blank control group and the overexpressed control group (P<0.01). Western blot results showed that compared with the blank control group and the overexpression control group, the expression level of E-cadherin protein in MCF-10A cells in the overexpression Armcx3 group was significantly decreased (P<0.0001), and the expression level of Vimentin protein was significantly increased (P<0.05). Conclusion Armcx3 is highly expressed in breast cancer, and overexpression of Armcx3 promotes the proliferation, migration, and epithelial mesenchymal transformation of MCF-10A cells