OBJECTIVE：To stu dy the regulation effects of Huanglian jiedu decoction on M 1 and M 2 macrophage polarization in atherosclerosis （AS）model mice ，and to elucidate its mechanism of AS prevention and treatment. METHODS ：Sixty ApoE －/－ male mice were randomly divided into blank control group ，model group ，simvastatin group [positive control ，5 mg/（kg·d）]， Huanglian jiedu decoction low-dose ，medium-dose and high-dose groups [ 5，10，20 mg/（kg·d），by crude drug] ，with 10 mice in each group. Except for blank control group ，other groups were given high-fat diet to induce AS model. After modeling ， administration groups were given relevant medicine intragastrically ；blank control group and model group were given normal saline intragastrially，once a day ，for consecutive 4 weeks. After medication ，the contents of triglyceride （TG），total cholesterol （TC）， low density lipoprotein cholesterol （LDL-C） and high density lipoprotein cholesterol （HDL-C） in serum were detected by automatic biochemical analyzer. Sirius red staining was used to observe the formation of collagen fibers in the aorta of mice. The serum contents of iNOS and CD 206 were determined by ELISA. mRNA expression levels of IL- 1β，iNOS，TNF-α，YM1 and Fizz1 in the aorta were detected by RT-PCR. RESULTS ：Compared with blank control group ，the serum contents of TC ，TG， LDL-C and iNOS ，mRNA expression levels of IL- 1β，iNOS，TNF-α in the aorta were significantly increased in model group（P＜ 0.05 or P＜0.01），while the serum contents of HDL-C and CD 206 and mRNA expression levels of IL- 10，YM1，Fizz1 in the aorta were significantly decreased （P＜0.01）. There was a thick layer of collagen fibers under the endothelium of aorta. Compared with model group ，above serum indexes of mice were improved significantly in administration groups （P＜0.05 or P＜0.01）；mRNA expression levels of IL- 1 ，iNOS and TNF-α in the aorta in Huanglian jiedu decoction medium-dose and high-dose groups were decreased significantly （P＜0.01），while mRNA expression levels of IL- 10，YM1 and Fizz 1 were increased significantly （P＜0.05 or P＜0.01）. The vascular endothelium was relatively smooth. CONCLUSIONS ：Huanglian jiedu decoction can inhibit the polarization of M 1 macrophages and promote the polarization of M 2 macrophages，reduce the inflammatory reaction ，maintain the stability of atherosclerotic plaque in artery ，so as to play the role of anti-AS.