Background: Knee osteoarthritis (KOA) is a major public health issue causing chronic disability as well as a burden on healthcare resources. In China, a herbal drug tablet has been used as an effective and conventional therapy to alleviate clinical symptoms caused by KOA. However, evidence gathered from systematic reviews or randomized controlled trials that validated herbal drugs for the management of osteoarthritic pain is weak. The purpose of this study is to explore the efficacy and safety of the Shaoyao Shujin tablet for the management of KOA in a short-term study. Methods/Design: This trial is a multicenter randomized, double-blind, placebo-controlled study. A total of 276 patients will be randomized into 3 groups: (1) the high-dose Shaoyao Shujin tablet group (HD group), (2) the low-dose Shaoyao Shujin tablet group (LD group), and (3) the placebo tablet group (control group). In the three groups, four tablets will be administered three times per day for 6 weeks. Follow-up will be at regular intervals during a 10-week period with the Western Ontario and McMaster Universities Index (WOMAC) score, visual analog scale (VAS) score, and rescue medication use assessed as outcome measures. Discussion: This study will provide clinical evidence on the efficacy and safety of the Shaoyao Shujin tablet in treating KOA.