[ObjectivejTo explore the therapeutic mechanism of Tongbiling (TBL) prescription for rheumatoid arthritis (RA) by observing the effects of TBL on inflammation and expression of vascular endothelial growth factor (VEGF) in synovium of rats with collagen-induced arthritis (CIA) .[Methods]CIA rat models were established by subcutaneous injection of type II collagen. Pathological sections of synovium in knee joint were made after medication for 37 days and then stained by HE method and immunohistochemical method respectively. Infiltration of inflammatory cells and hyperplasia of macrophages A and fibrous tissue in HE-stained pathological sections were observed under microscope and expression of VEGF was observed by semi-quantitative immunohistochemical method. [ Results ] Infiltration of inflammatory cells and hyperplasia of macrophages A and fibrous tissue in high-dose TBL group were inferior to those in model group (P 0.05); both TBL and Radix Tripterygii Wilfordii at high dose decreased the expression of VEGF (P