Objective:To evaluate the effects of different interventions for flavum ligament in clinical results and CT outcomes on microendoscopic discectomy(MED). Methods:Ninety-two patients were divided into two groups at random. Both groups were disposed with microendoscopic discectomy,differentiated from each other by flavum ligament operation. Data at 1 day pre-operation,3 weeks,3 months and 1 year post-operation were followed up,respectively. The clinical effects were assessed by Oswestry Disability Index,and the improvement rates were also calculate. CT films taken from 1 year follow-up were graded,and the constitution of different graded cases were analyzed between 2 groups. The Correlation between graded CT films and corresponding improvement rates were analyzed. Results:Both ODI at 1 day pre-operation and improvement rates at 3 weeks post-operation were observed no significant difference(P > 0.05). At 3 months and 1 year post-operation,the improvement rates between two groups had significant difference(P < 0.001). In group A,the improvement rates increased at 3 months post-operation in contrast to 3 weeks post-operation(P > 0.05),which declined 1 year later(P < 0.05). No significant difference between 3 weeks and 1 year post-operation was observed(P > 0.05). In group B,the improvement rates increase continually. There was no significant difference(P > 0.05) between 3 weeks and 3 months post-operation,whereas significant differences were observed between 1 year and 3 months,1 year and 3 weeks(P < 0.05). At 1 year post-operation,the constitution of different graded CT films between two groups had significant difference(P < 0.05). Correlative analysis revealed obvious difference between each graded CT and corresponding improvement rate(P < 0.01). Conclusion:Different interventions for flavum ligament can obviously affect the variances of epidural fibrosis that CT films manifested. There was a negative correlation between fibrosis degrees and clinical effects.