Abstract: OBJECTIVE To explore the proliferative inhibition effects of Lingba Junzhi alkaline constituents on human non-small cell lung cancer A549 cells and its mechanism via in vitro cell culture.METHODS The alkaline constituents were obtained by alkali-solution and acid-isolation extraction， and solvent extraction of Lingba Junzhi methyl alcohol extract parts; HPLC was applied to verify the existence of Crontonside. MTT assay， soft agaragar assay， PT single-stain and immunofluorescent staining were later used to observe its effects on inhibiting A549 cell proliferation， tumor formation， growth cycle distribution and cytoskeleton destruction.RESULTS Crontonside did exist in Lingba Junzhi alkaline constituents， which significantly inhibited A549 proliferation and reduced cell clone formation， delayed the cell circle in G2 period and caused certain damage to the cytoskeleton.CONCLUSION Lingba Junzhi alkaline constituents can inhibit in vitro A549 cell proliferation and its mechanism may be related to its decreasing clone formation ability and damaging cytoskeleton.