Osteoarthritis (OA) is a chronic degenerative disease, which can cause a series of symptoms including pain and functional limitation, thus severely decreasing quality of life. OA pathogenesis can be categorized into four levels, including risk factors, potential mechanisms, intraarticular degeneration phenotype, and substantive histological changes. Moderate exercise can alleviate OA at all levels of pathogenesis, while excessive exercise may have adverse effects. Based on rat-related original research, the parameters of moderate exercise and the effect of improving osteoarthritis have been comprehensively summarized. Based on the extensive randomized controlled trial studies, results show various moderate exercises can improve the symptom and prognosis of OA in clinical settings. This review gives an overview of the pathogenesis of OA and the mechanisms as well as clinical examples of moderate exercise treatment, aimed at providing rationale and evidence for moderate exercise in the treatment of OA to facilitate the provision of appropriate exercise therapy for OA patients.