Objective We investigated the inhibitory effect of Forsythia suspensa extract ( FSE ) on lipopolysaccharide ( LPS)-induced inflammation and establishment of an LPS-induced polarization model of RAW264. 7 cells. Methods MTT assays were used to assess cytotoxic effects of FSE and LPS on RAW264. 7 cells. Inverted microscopy was used to assess morphological changes of cells after stimulation with LPS and various concentrations of FSE. An enzyme marker was used to detect nitric oxide (NO) in culture supernatants. Fluorescence microscopy was used to detect intracellular reactive oxygen species (ROS) and apoptosis. ; Real-time PCR was used to detect iNOS expression in macrophages. iNOS, TNF-α, IL-1β, IL-6, IL-10, Arginase-1 and CD206 mRNA expression was measured by Real-time PCR. Results FSE was not cytotoxic at 50 μg / mL. At 36 h of LPS stimulation, various concentrations of FSE inhibited LPS-induced morphological changes, NO production and FSE inhibited LPS-induced the reduction of reactive oxygen species (ROS) and apoptosis. Expression of M1-type marker genes (TNF-α, IL-1β, iNOS and IL-6) in RAW264. 7 cells was significantly increased after treatment with various concentrations (100, 250, 500 and 750 ng / mL) of LPS for 24 h or with 500 ng / mL LPS for various times. The mRNA levels of M2 marker genes ( IL-10, Arginase-1 and CD206) were significantly decreased in RAW264. 7 cells. FSE decreased the expression of LPS-induced M1 marker genes and increased expression of M2 marker genes. Conclusions FSE inhibits LPS-induced inflammatory responses by inhibiting RAW264. 7 cell apoptosis and promoting polarization.