Abstract: OBJECTIVE To investigate the anti-breast cancer activity and related mechanism of total flavone from Eupatorium lindleyanum DC.(TFE). METHODS MTT assay was used to detect the effect of TFE on the proliferation of breast cancer cells (MCF-7, T47D, MDA-MB-231, MDA-MB-468) and human normal mammary cells(MCF-10A). Flow cytometry was used to determine the effect of TFE on cell cycle and apoptosis in breast cancer. Acridine orange(AO) staining was used to detect the effect of TFE on autophagy. The changes of cell cycle, apoptosis, autophagy related proteins, as well as the changes of PI3K/Akt signaling pathway related proteins were detected by Western blotting assay. Xenograft model in nude mice of MDA-MB-231 cells was established to observe the antitumor activity in vivo of TFE. RESULTS TFE could significantly inhibit the proliferation of breast cancer cells in a dose-dependent manner, but had no significant inhibitory effect on human normal mammary cells. TFE could induce cell cycle arrest at G₂/M phase, and the expression of cell cycle related proteins Cyclin B1 and cdc2 were decreased, while p-cdc2 was increased. TFE could significantly increase the apoptosis rate of breast cancer cells, and the expression of apoptotic protein Bad and Bax were increased, while the anti-apoptotic protein Bcl-2 was decreased. TFV could induce autophagy in breast cancer cells, and the expression of autophagy related protein LC3-Ⅱ increases, while the expression of p62 decreases. TFE significantly inhibited the phosphorylation of PI3K and Akt. TFE inhibited tumor volume in nude mice in vivo. CONCLUSION TFE inhibits the growth of breast cancer cells in vivo and in vitro by inhibiting the PI3K/Akt signaling pathway, cell cycle arrest, inducing apoptosis and autophagy.