Aim To investigate the effects of paeonol on lipopolysaccharide ( LPS) and adenosine 5′-triphos-phate ( ATP) induced NLRP3 inflammasome activation in primary rat microglia and the mechanisms responsi-ble for this anti-inflammatory effects. Methods Pri-mary rat microglia were identified immunohistochemi-cally using the cluster of differentiation 11 b ( CD11 b ) antibody. Proinflammatory cytokine IL-1β was deter-mined by ELISA. Western blot was performed to ob-serve the protein expression of NLRP3 , ASC and caspase-1 in cultured primary rat microglia. The level of intracellular reactive oxygen species ( ROS) was mo-nitored by using the fluorescent probe 2′, 7′-dichlo-rofluorescein diacetate ( DCFH-DA ) . Results LPS (0. 5 mg · L-1 )/ATP ( 5 mmol · L-1 ) significantly increased intracellular ROS level and IL-1β secretion and upregulated NLRP3 , ASC and caspase-1 protein expression in primary rat microglia. Paeonol signifi-cantly decreased intracellular ROS level and IL-1β se-cretion, and inhibited LPS/ATP induced overexpres-sion of NLRP3 , ASC and caspase-1 in cultured primary rat microglia. Conclusion Paeonol can inhibit LPS/ATP induced NLRP3 inflammasome activation in pri-mary rat microglia, and this inhibitory effect may be through the suppression of intracellular ROS.