Objective To investigate the effects of Loropetalum chinense extracts on the proliferation of lung adenocarcinoma A549 cells cultured in vitro. Methods CCK-8 assay was performed to evaluate the effect of Loropetalum chinense extracts on the proliferation of A549 cells, and the clonal growth ability of A549 cells was determined by clone formation assay. Flow cytometry Annexin V-APC/PI double staining was used to measure the apoptosis of A549 cells. Western blot was used to measure the expressions of apoptosis-related proteins Bax, Fas, Bcl-2 Caspase3 and cleaved-Caspase 3. Results Loropetalum chinense extracts significantly inhibited the proliferation and colony formation of A549 cells in a time- and dose-dependent manner. The viability of A549 cells decreased by 50% after 48h treatment of 0.5mg/ml extracts, and 100% inhibition of colony formation rate achieved when the cells were treated with 40μg/ml extracts for 14 days. When A549 cells were treated with Loropetalum chinense extracts for 24h, apoptotic rates increased in a dose-dependent manner. Compared with the control group, the protein levels of Fas, Bax, Caspase3 and cleaved-Caspase3 were up-regulated, while Bcl-2 was down-regulated. Conclusion Loropetalum chinense extracts inhibit the growth of human lung adenocarcinoma cells in vitro, and the mechanisms may be related to the activation of mitochondrial and death receptor apoptosis pathway.