Background Rheumatoid arthritis (RA), a chronic autoimmune disease, has a high incidence and disability rate, causing patients significant discomfort. Although several medicines can be effective, they are also associated with significant adverse effects. In contrast, fumigation as one of the most often used traditional Chinese medicine (TCM) external therapy has shown both efficacy and safety with less side effect. In light of this, we complement western medicine treatment with TCM fumigation therapy to improve patients' clinical efficacy, alleviate symptoms, and improve prognosis. Objective To investigate the therapeutic effect of TCM fumigation and modern medicine combined therapy in treating RA patients with cold-dampness Bi syndrome. Methods A single-center, randomized, controlled study was designed. From January 2022 to December 2022, a total of 60 RA patients with cold-dampness Bi syndrome were enrolled in the study. The control group (30 cases) received conventional modern medicine treatment with methotrexate for 4 weeks, while the observation group (30 cases) for 4 weeks received a combination of TCM fumigation treatment and conventional modern medicine. The effects of the two groups were comprehensively compared, including the changes in TCM symptom scores and laboratory indicators, as well as the use of visual analogue scale (VAS) and health status rating scale (HAQ) before and after treatment. Results The total effective rate of the observation group was 93.3%, which was significantly higher than that of the control group, which is 70% (P < 0.05). Before treatment, there were no significant differences in joint functional activity, pain visual analogue scale (VAS), health assessment questionnaire (HAQ-DI) and laboratory indexes between the two groups (P > 0.05). After treatment, each group compared to their initial condition, respectively, showed major improvement of joint functional activity and significantly decreased VAS, HAQ-DI, and RA-related biomarkers (P < 0.05); inter-group comparison of these indicators showed significanty further enhanced effect of TCM fumigation combined therapy on the RA-related biomarkers and joint functional activity of patients (P < 0.05), yet the control group receiving only modern medicine showed better results of the VAS and HAQ-DI . Conclusion The TCM fumigation combined therapy is effective to treat RA patients with cold-dampness Bi syndrome, and to enhance their life quality, improving the joint function, and reducing inflammation.