OBJECTIVE To explore the mechanism of action of Qingre huatan huoxue decoction against atherosclerosis （AS）based on macrophage polarization. METHODS Using atorvastatin served as the positive control， the drug-containing serum of the Qingre huatan huoxue decoction was prepared to treat RAW264.7 macrophages. Macrophage viability， apoptosis rate， and the fluorescence intensities of CD86 and CD206 were measured， along with the levels of tumor necrosis factor-α （TNF-α） and interleukin-1β （IL-1β）. Apolipoprotei n E-deficient （ApoE －/－ ） mice （AS model mice） fed with a high-fat diet were randomly assigned to model group， atorvastatin group （2.6 mg/kg）， and low-， medium- and high-dose groups of Qingre huatan huoxue decoction （90， 180， 360 mg/kg）， respectively. C57BL/6J mice fed with a standard diet served as the normal control group， with 10 mice per group. The treatment group mice were administered the corresponding drugs intragastrically， once daily， for 8 consecutive weeks. Serum levels of TNF-α and IL-1β were measured in all groups. Lipid deposition in the aorta （assessed by the percentage of plaque in the entire aorta and aortic root） and morphological changes in the aortic root were observed. Expression levels of CD86 and CD206 in aortic tissue， as well as the protein expression levels of inducible nitric oxide synthase （iNOS）， arginase-1 （Arg-1）， AMP-activated protein kinase （AMPK）， phosphorylated AMPK （p-AMPK）， and peroxisome proliferator-activated receptor γ （PPAR-γ） in aortic tissues were all detected. RESULTS Cell experiment results showed that， at concentrations of 5-100 μg/mL， the drug-containing serum of the Qingre huatan huoxue decoction significantly increased RAW264.7 cell viability （ P ＜0.05）. The drug-containing serum of the Qingre huatan huoxue decoction at concentrations of 10， 50， and 100 μg/mL， along with atorvastatin， significantly reduced apoptosis rates， CD86 fluorescence intensity， and TNF-α and IL-1β levels in RAW264.7 cells， while markedly enhancing CD206 fluorescence intensity （ P ＜0.05）. Animal experiment results showed that， compared with the model group， all dosage groups of Qingre huatan huoxue decoction and the atorvastatin group showed significantly reduced/down-regulated levels of TNF-α and IL-1β in serum， along with decreased aortic total and root plaque percentages， CD86 expression， and iNOS protein expression. CD206 expression and Arg-1， p-AMPK/AMPK， PPAR-γ protein expression were significantly up-regulated （ P ＜0.05）. Pathological morphology of the aorta showed varying degrees of improvement. CONCLUSIONS The formula of Qingre huatan huoxue decoction exerts its anti-AS effects by regulating macrophage polarization， increasing the proportion of M2 macrophages， thereby effectively inhibiting AS plaque formation and reducing inflammatory responses.