Background: Knee osteoarthritis (OA) is a common clinical degenerative disease of the joints, which is prone to occur in middle-aged and elderly people. At present, the disease cannot be cured, it is mostly treated with drugs to relieve symptoms, improve joint function, protect cartilage, such as glucosamine, anti-inflammatory and analgesic drugs, and but the efficacy is not lasting and the recurrence rate is high. Hydrotherapy has become a long-term alternative therapy in China and is receiving increasing attention. We perform a protocol for systematic review and meta-analysis to determine the efficacy and safety of a hydrotherapy program in individuals living with knee OA. Methods: This protocol will be designed in accordance with the preferred reporting items for systematic reviews and meta-analysis protocols. It is registered on the international prospective register of systematic reviews (No. CRD42022365564). We will search the following databases: The Cochrane Skin Group Trials Register, MEDLINE, EMBASE, The Cochrane central register of controlled trials, Chinese biomedical literature database, Chinese medical current content and China national knowledge infrastructure. The risk of bias of the included studies will be appraised using the Cochrane collaboration tool. Statistical analysis will be performed using IBM SPSS Statistics (Armonk, NY). Results: This systematic review will summarize the short- and long-term clinical outcomes of hydrotherapy for knee OA. Conclusion: The findings from this review will establish the quality of currently available evidence, which will determine the need for further studies to establish the true effect size of hydrotherapy in knee OA.