Abstract: Objective To explore the effects of stellettin B on proliferation， apoptosis of nonsmall cell lung cancer（NSCLC） cells and its possible active mechanism. MethodsThe A549 and NCI-H1299 cells were treated with different concentrations of stellettin B （01， 1， 10， 100μmol／L）. The MTT method was used to measure the proliferation inhibition rate at 24th， 48th， 72nd and 96thh treated with different concentrations of stellettin B. The Hoechst staining was employed to detect the cell apoptosis index at 24th and 48th h after treatment with stellettin B. The Annexin-FITC／PI double staining and PI staining were employed to detect cell apoptosis and cell cycle distribution at 48th h via flow cytometry. The Western blotting was used to measure the protein levels of cell cyclerelated genes （cyclin A， CDK2 and p21CIP1） at 48th h after treatment. Results The stellettin B of different concentrations could increase the proliferation inhibition rates in a dose and timedependent manner. After being treated by stellettin B for 24 and 48h， there were increased apoptosis index， apoptosis rate in a dose dependent manner. With the increase of stellettin B，there were increased G0／G1 phase cell percentage and protein level of p21CIP1 but decreased S and G2／M phase cell percentages and protein level of cyclin A and CDK2 with statistical difference （P＜0.05）. Conclusion Stellettin B can inhibit the proliferation of NSCLC cells as well as inducement of apoptosis and cell cycle arrest， possibly by influencing the expressions of cyclerelated genes.