To study the chemical constituents of Stephania kwangsiensis Lo. and to explore the effects of corydine on proliferation and apoptosis of lung adenocarcinoma NCI-H446 cells. Chemical structures were elucidated by MS, 1H-NMR and 13C-NMR. Effects of different concentrations of corydine on proliferation of lung adenocarcinoma NCI-H446 cells were determined by MTT assay. Effects of corydine on apoptosis rate of NCI-H446 cells were determined by flow cytometry. Three types of alkaloids were isolated from root tubers of Menispermaceae Stephania plant Stephania kwangsiensis Lo. Three different concentrations of corydine (20, 10, 5 Lg/ml) could all significantly increase the apoptosis rate of NCI-H446 cells after 48 h of treatment compared to the control group. Corydine can inhibit the proliferation of lung cancer NCI-H446 cells and induce their apoptosis.