Synovitis with pigmented villous nodules is a common form of synovial lesion, and there are two types: villous and nodular. It is most common in young people, often in the knee joint, but can also develop in other joints, but is less common. There are no significant systemic symptoms and the patient does not have a high body temperature. The main symptom is diffuse swelling of the knee joint with mild pain and sometimes slightly high local skin temperature, and the limitation of joint movement is not obvious. When the knee joint is touched by hand, the thickened synovial membrane in the suprapatellar bursa area can be touched with a sponge-like sensation, and a fluctuating sensation can be touched if there is a lot of fluid accumulation. Whether diffuse or focal, patients with longer disease duration have mild muscle atrophy, which, together with the swelling of the knee joint itself, makes the knee joint appear particularly enlarged. Joint cavity aspiration can produce bloody or coffee-colored fluid, and this fluid accumulation is very specific and has diagnostic significance. Treatment of pigmented nodular villonodular synovitis is mainly surgical. Currently, the diseased synovial membrane is basically removed clinically using arthroscopic surgery, which can be supplemented with radiotherapy and Chinese medicine for evidence-based treatment after surgery.