BackgroundRheumatoid arthritis (RA) is a common chronic autoimmune disease that seriously affects the quality of life of patients because of damage to joints. Presently, RA is mainly treated with disease-modifying antirheumatic drugs (DMARDs) or biological agents; however, they offer limited efficacy in some patients. Therefore, additional therapeutic strategies need to be developed. Yishen Tongbi decoction is a traditional Chinese medicine formulation widely used to treat RA in China. However, currently, there is insufficient evidence to recommend its use for the treatment of RA. Therefore, we aim to verify the efficacy of Yishen Tongbi decoction to treat RA by a noninferiority trial, and to provide a basis for its use with a full-scale clinical trial.Methods/designOne hundred eligible patients with RA will be randomized into two groups of 50 patients. One group will receive Yishen Tongbi decoction and placebo replacing methotrexate (MTX), while the other group will receive MTX and placebo replacing Yishen Tongbi decoction. Patient’s whose visual analogue scale score for pain is greater than 40 mm will be administered nonsteroidal anti-inflammatory drugs (such as enteric-coated diclofenac sodium, 25 mg three times a day); administration of all medications will be recorded. The clinical indicators of patients and their disease activity will be assessed at baseline and at 4, 12 and 24 weeks after treatment initiation. The primary outcome of efficacy will be the proportion of patients who demonstrate a favourable response based on their Clinical Disease Activity Index score at 24 weeks after treatment. All adverse events will be reported.DiscussionTraditional Chinese medicine theory and modern western medicine research have identified the efficacy of Yishen Tongbi decoction to treat RA. Previous clinical observation and efficacy trials of Yishen Tongbi decoction in animal models for the treatment of RA has demonstrated significant effect. Because of the potential benefits of Yishen Tongbi decoction in the treatment of patients with RA, we designed this double-blind, prospective, randomized controlled trial; the results and conclusions of the trail will be published after the completion of the study.Trial registrationChinese Clinical Trials Registry, ChiCTR1900024902. Registered on 3 August 2019.