To investigate the efficacy and mechanisms of matrine, a component derived from Sophora flavescens in treatment of rheumatoid arthritis (RA), a rat model of RA was established. Compared to control rats, matrine significantly mitigated inflammation and severity of RA (paw volume and articular index (AI) score). Using either mice splenic T cells stimulated with PMA/ionomycin or rat splenic T cells, the levels of Th1 and Th2 responses were determined by flow cytometry, quantitative RT-PCR, and ELISA. Furthermore, the levels of NF-κBp65 (RelA), IκBα, and phosphor-IκBα in T cells were determined by Western blot. Our study found that matrine modulated the imbalance of Th1 and Th2 cytokine responses in rats with RA by reducing the levels of Th1 cytokines (IFN-γ, TNF-α, IL-1β), but increasing Th2 cytokine (IL-4 and IL-10) through attenuating the NF-κB signaling in T cells, suggesting matrine as a promising drug for intervention of RA.