Objective: To investigate the effects of autophagy inhibitor 3-methyladenine (3-MA) on growth and Notch1 protein expression in human colon cancer SW480 cells. Methods: In SW480 cells after exposure to 3-MA (5 mmol/L) for 24 h (using untreated SW480 cells cultured for the same time period as control), the Notch1 protein expression was determined by immunohistochemical staining and Western blot analysis, and cell proliferation and apoptosis was detected by CCK8 assay and Annexin/PI double staining, respectively. Results: Both results of immunohistochemical staining and Western blot analysis showed that the Notch1 protein expression was significantly down-regulated in SW480 cells after 3-MA treatment (both P<0.05). Results of cell proliferation and apoptosis assay showed that the proliferation was significantly decreased while apoptosis rate was significantly increased in SW480 cells after 3-MA treatment (both P<0.05). Conclusion: 3-MA can suppress the proliferation and promote apoptosis of colorectal cancer cells, which may probably be associated with its inhibition of notch1 protein expression and thereby altering autophagy level of the cells.