OBJECTIVE：To investigate the effects of metformin on malignant phenotype of pancreatic cancer BxPC- 3 cells. METHODS：Using human pancreatic cancer BxPC- 3 cells with natural deletion of Smad4 gene as reaserch objects ，CCK-8 assay and flow cytometry were used to detect the proliferation and apoptosis of BxPC- 3 cells after treated with different doses of metformin（5，10，20 mmol/L）for 24 h. The cell survival rate and apoptosis rate were calculated. Transwell assay was used to test the migration of cells after treated with different doses of metformin （10，20 mmol/L）for 24 h. The number of migrating cells was recorded. qRT-PCR and Western blotting assay were performed to determine mRNA and protein expression of E-cadherin ，Vimentin and RGC- 32 in cells. RESULTS ：Compared with control group and 5 mmol/L metformin group ，survival rate of cells were decreased significantly in 10，20 mmol/L metformin groups ，while apoptosis rate was increased significantly ；the apoptosis rate in 20 mmol/L metformin group was significantly higher than 10 mmol/L metformin group （P＜0.05）. Compared with control group ， the number of migrating cells was decreased significantly in 10，20 mmol/L metformin groups ，and the 20 mmol/L metformin group was significantly lower than 10 mmol/L metformin group （P＜0.05）. Relative mRNA and protein expression of E-cadherin were increased significantly in 10，20 mmol/L metformin groups ，and relative mRNA expression of E-cadherin in 20 mmol/L metformin group was significantly higher than 10 mmol/L metformin group. Relative mRNA expression of Vimentin in 10 mmol/L metformin group ，relative mRNA and protein expression of Vimentin in 20 mmol/L metformin group ，relative mRNA and protein expression of RGC- 32 in 10，20 mmol/L metformin groups were decreased significantly ；relative mRNA and protein expression of Vimentin as well as mRNA expression of RGC- 32 in 20 mmol/L metformin group were significantly lower than 10 mmol/L metformin group （P＜0.05 or P＜0.01）. CONCLUSIONS ：Metformin can inhibit the proliferation and migration of pancreatic cancer cells through smael-independent pathways in a dose- dependent manner ，and promote their apoptosis ，which is associated with the inhibition epithelial- mesenchymal transition and the expression of RGC- 32 of pancreatic cancer.