ObjectiveTo explore the effect and mechanism of modified Dingjingtang in regulating the Toll-like receptor 2 （TLR2）/nuclear factor （NF）-κB/NOD-like receptor protein 3 （NLRP3） signaling pathway to inhibit inflammatory skin lesions in the rat model of acne. MethodsForty-eight rats were randomized into the normal， model， low-， medium-， and high-dose （8.1， 16.2， and 32.4 g·kg^-1） modified Dingjingtang， and doxycycline hydrochloride （0.27 g·kg^-1） groups， with 8 rats in each group. Rats in other groups except the normal group were modeled by intradermal injection and intraperitoneal injection of Propionibacterium acnes. After successful modeling， rats in the intervention groups were treated with corresponding agents by gavage， and those in the normal and model groups with an equal volume of normal saline， once a day for 14 consecutive days. Then， the samples were collected. The general conditions， ear thickness， and body weight changes of rats were observed. Biochemical methods were used to determine superoxide dismutase （SOD） and malondialdehyde （MDA） levels in the ear tissue. Hematoxylin-eosin staining and Masson's staining were used to observe the pathological changes and collagen deposition， respectively， in the ear tissue. Immunohistochemistry was employed to determine the interleukin （IL）-1β level in the ear tissue. Enzyme-linked immunosorbent assay was adopted to measure the levels of IL-1β， tumor necrosis factor （TNF）-α， and IL-6 in the serum. The total antioxidant capacity method was adopted to assess the reactive oxygen species （ROS） content in the ear tissue. Western blot and real-time fluorescence quantitative polymerase chain reaction were employed to determine the protein and mRNA levels， respectively， of TLR2， myeloid differentiation factor 88 （MyD88）， NF-κB， NLRP3， and cysteinyl aspartate-specific proteinase-1 （Caspase-1） in the ear tissue. ResultsCompared with the normal group， the model group had increased ear skin thickness （P<0.01）， elevated ROS and MDA levels （P<0.01）， reduced SOD content （P<0.05）， and increased collagen deposition （P<0.01） in the ear tissue. In addition， the model group showed raised IL-1β， IL-6， and TNF-α levels in the serum （P<0.01） and up-regulated mRNA and protein levels of TLR2， MyD88， NF-κB， NLRP3， and Caspase-1 （P<0.01）. Compared with the model group， the high- and medium-dose modified Dingjingtang groups showed significant improving effects regarding the above indicators （P<0.05， P<0.01）. ConclusionModified Dingjingtang can ameliorate the inflammatory skin lesions in the rat model of acne by regulating the TLR2/NF-κB/NLRP3 signaling pathway.