Abstract: Objective To evaluate the effect of arthroscopic plastic operation on discoid medial meniscus. Methods From June 2003 to April 2008,4 cases of discoid medial meniscus underwent arthroscopic plastic operation.Ablation was carried out with clamps,decorating and sharpening cutter or radiofrequency knife from an anteriomedial or an anteriolateral incision made on the knee joint.A 6mm peripheral rim of the meniscus was reserved.Arthroscopic removal of the injured meniscus and cartilage was performed with a radiofrequency knife. Results All the patients were followed up for an average period of 35 months.The JOA score was used to evaluate the therapeutic effect of arthroscopic plastic operation.The average JOA score was 47.5（40-55）and 81.3（75-85）before and after operation,respectively.Excellent and good effects were achieved in 3 cases and 1 case,respectively. Conclusion Rather good therapeutic effect can be achieved in treatment of discoid medial meniscus with arthroscopic plastic operation of meniscus.