Arthroscopy can treat many types of intra-articular diseases, including rheumatoid arthritis, gouty synovitis, pigmented villous nodular synovitis, synovial chondromatosis, intra-articular cysts, septic arthritis, and joint tuberculosis. Meanwhile, for difficult cases with unclear diagnosis, arthroscopic examination is feasible to further clarify the diagnosis or take pathological biopsy. Joint stiffness caused by trauma or degeneration can be loosened under arthroscopy. Modern arthroscopy can complete the diagnosis and treatment of shoulder, elbow, wrist, hip, knee, ankle and other parts of the disease.