Objective To explore the effect of arthroscopy on diagnosing and treating suppurative arthritis of knee joint. Methods The clinical data of 22 patients with suppurative arthritis of knee joint diagnosed between January 2012 and December 2013 were analyzed retrospectively, including 13 males and 9 females with the age of 7-56 years (average 28.5 years). The duration of disease history was from 7 days to 4.5 months with the average of 2.8 months. All of the patients had swelling, pain, and limitation of motion of the knee joint in different degrees. Among them, 20 patients were diagnosed definitely and remaining 2 were osteoarthritis with atypical infections. Patients were investigated by Lysholm questionnaires during the follow-up period. Results All of the 22 patients were followed up for 3-10 months with the average of 8.5 months. The diagnosis was confirmed by pathological and arthroscopic examination after the surgery, and no recurrence was found. Lysholm score ranged from 77 to 99 with the average of 92.8. Only 1 patient had the motion range of 10-40°of the knee joint after several treatment. Conclusion Early arthroscopic treatment for suppurative arthritis of knee joint with continuous postoperati ve lavage and irrigation combined with comprehensive physiotherapy and rehabilitation has the advantages of high efficacy, maximum recovery of knee function, and quick recovery, which should be promoted in the clinical application