Objective: Investigate the clinical effect of arthroscopic debridement combined with continuous lavage in the treatment of pyogenic arthritis of the knee. Methods: Forty patients with suppurative knee arthritis were retrospectively analyzed from January 2013 to December 2016 in the Lanzhou General Hospital of the People’s Liberation Army. Among them, 18 patients were male 22 were female. A patients suffered from single knee joint disease. The patients were divided into a drainage combined with antibiotic treatment group (the catheter group) and an antibiotic therapy alone group (the non-catheterization group). All patients underwent arthroscopic exploration cleaning combined lesion synovectomy, intraoperative specimen pathology diagnosis, postoperative return: chronic suppurative inflammation; catheter group patients underwent catheter lavage for about 1 week, conventional anti-inflammatory, analgesic, in the extraction of drainage tube after routine early functional exercise. The patients in the non-catheterization group received routine anti infection and analgesia after arthroscopic debridement, and the knee joint function was resumed at the early stage. Through the follow-up of patients with different follow-up time of CRP, erythrocyte sedimentation rate, visual analogue scale (VAS) score and Lysholm score of knee joint function evaluation of the therapeutic effect of two groups. Results: All patients were followed up for 6–12 months. The recovery of CRP and ESR in the postoperative group was faster than that in the non-catheterization group, and the data of the two groups were statistically significant (P<0.05). After the operation, the VAS score in the catheterization group was shorter than that in the non-catheterization group (P<0.05) after 1 month, and the knee joint Lysholm score in the catheterization group was higher than that in the non-catheterization group after 1 and 3 months (P<0.05). One year later, all patients after surgery of knee joint function were stable, no significant differences between the two groups; however, there were 3 cases in the non-catheter group that had recurrent suppurative arthritis 2 months after surgery, after flushing the catheter and combined with antibiotic treatment, there was no recurrence. Conclusion: Arthroscopic debridement has a high cure rate for pyogenic arthritis of the knee. Arthroscopic synovectomy combined with postoperative continuous lavage is helpful to enhance the therapeutic effect and reduce the recurrence probability.