Objective To investigate the possible mechanism of Wendan Decoction（温胆汤） in the treatment of obesity. Methods A rat model of obesity induced by high-fat diet was randomly divided into model group and Wendan Decoction group

with 8 rats in each group

and 8 healthy rats were set as normal group. After successful modeling

the rats in each group were fed with basal diet. The rats in Wendan Decoction group were given 15 g/（ kg·d） of Wendan Decoction. The model group and the normal group were treated with the same amount of distilled water

for 6 weeks. The body weight

Lee’s index

and obesity rate of each group were compared. Serum leptin and blood lipids including total cholesterol（ TC）

triglyceride（ TG）

low density lipoprotein cholesterol（ LDL-C） and high-density lipoprotein cholesterol（ HDL-C）) and hypothalamic signal transducers and activators of transcription 3（ STAT3）

suppressor of cytokine signaling 3（ SOCS3） mRNA and protein expression were measured. Results Compared with the normal group

the body weight and blood lipid levels（ except HDL-C）

hypothalamic STAT3 mRNA and protein expression

and SOCS3 mRNA and protein expression were decreased in the model group（ P < 0. 01）. Compared with the model group

the Lee’s index

body weight

blood lipid level（ except HDL-C）

hypothalamic STAT3 mRNA and protein expression were significantly decreased

and SOCS3 mRNA and protein expression were significantly increased（ P < 0. 01）. The obesity rate of the model group was 26. 36%

and that of the Wendan Decoction group was 1. 06%. Conclusion Wendan Decoction has a good lipid-lowering effect

which may regulate the body’s Leptin level by regulating JAK2/STAT3 signaling pathway

thus correcting the body’s metabolic abnormalities.