Objective:To study the effects of Mycobacterium Phlei on cell apoptosis in SPCA/Ⅰ human lung cancer cells. Methods:The Cells were cultured in RPMI 1640 together with Mycobacterium Phlei at different concentrations for 36 hour. The changes of apoptosis of SPCA/Ⅰ human lung adenocarcinoma cells induced by Mycobacterium Phlei were detected by Annexin V: FITC Apoptosis detection kit,FACSAria flow cytometry and the inverted microscope. Results:The growth inhibitory rate had the positive correlations with concentrations of Mycobacterium Phlei on SPCA/Ⅰ human lung adenocarcinoma cells. Mycobacterium Phlei had significant effects on cell apoptosis in SPCA/Ⅰ human lung cancer cells. Typical apoptotic cells were seen whose bodies became smaller and rounder. Conclusion:Mycobacterium Phlei can induce apoptosis on SPCA/Ⅰ human lung adenocarcinoma cells and inhibit the tumor cell proliferation.