Abstract: Ojbective: To investigate the analgesic effects of intra-articular lidocaine and morphine accompanied with preoperative intravenous midazolam following local anesthesia arthroscopy procedures of knee joint.Methods: In this double-blind control study,105 patients were ready to undergo local anesthesia arthroscopy procedures of knee joint.They were randomized in three equal number groups: A（Lidocaine）,B（Lidocaine and Midazolam） and C（Lidocaine,Midazolam and Morphine）.Pain levels during the operation were measured by the Visual Analog Scale（VAS）.Results: The VAS scores of Group B and C were significantly lower than that of Group A（P＜0.05）.The scores of Group C was a little lower than that of Group B.However,there was no statistical significance between them（P＞0.05）.Conclusion: Preoperative intravenous midazolam can enhance the analgesic effects of lidocaine.It is also helpful for the patients to keep relaxed and makes the operation easier.