Abstract： Objective： To study the mechanism of alcohol extract of Juanbi Granules in inhibiting pathogenic Th17 cell expression to treat rheumatoid arthritis (RA)，and expound the molecular mechanism of yang- reinforcing theory in treating RA by Yang- Reinforcing School's Prof. WU Shengyuan. Methods： The models of DBA/1 mice with typeⅡ collagen- induced arthritis (CIA) were established，and the model mice were divided into the CIA model group (Model group) and the alcohol extract of Juanbi Granules intervention group (JBKL group)，with 10 mice in each group. The pathological injury of arthritis in CIA mice was detected by hematoxylin- eosin (HE) staining； the expression levels of Th17 cell and Treg cell were detected by flow cytometry；the expressions of genes related to Th17 cell were detected by quantitative real- time PCR. Results： Comparing with those in the Model group， the scores of joint histology in the JBKL group were decreased (P＜0.05). Comparing with that in the Model group，the Foxp3 + CD4 + T (Treg cell) expression level was up- regulated (P＜0.05). Comparing with those in the Model group，the IL- 17 + CD4 + proportion in lymphocytes of the spleen in the JBKI group was decreased (P＜0.05)，and the Treg/ Th17 ratio was increased (P＜0.05). The mRNA expression levels of IL-17A，IL-23p19，IL-21 and IFN-γ in the JBKL group were lower than those in the Model group，and the transcriptional level of Th17 specific transcription factor RORγt was lower than that in the Model group (P＜0.05). Conclusion： The alcohol extract of Juanbi Granules may inhibit Th17 cell differentiation by inhibiting the expressions of genes related to Th17 cell and up-regulate the Treg cell expression with negative regulation effect，which thus mediates the curative effect of Juanbi Granules on RA. This study provides scientific basis for treating RA with colddamp obstruction syndrome by the method of warming yang，dissipating cold and eliminating dampness， and enriches and develops the scientific connotations of theory of traditional Chinese medicine for the treatment of impediment syndrome.