Objective:To observe the medium-long term clinical effects of posterior lumbar canal decompression in aged Degenerative Spondylolisthesis. Method:The study involved 49 patients with aged Degenerative Spondylolisthesis whom were divided 2 groups as A and B according to their age and were received posterior lumbar canal decompression without internal fixation and fusion. The JOA score and The examination of X ray in the lateral and motive view of lumbar spine was used to evaluate the clinical effects. Result:Al patients were fol owed-up for 18 months to 66 months (average , 36.4 months) , which showed the satisfaction percentage was 88%in group A and 81% in group B. There were not any lumbar instability in any patient at final fol ow up. Conclusion: Lumbar canal decompression could improve the clinical outcome of aged degenerative spondylolisthesis without lumbar instability.