〔Abstract〕 Objective To explore the effect of non surgical treatment before periodontal flap surgery on the efficacy of severe periodontitis. Methods 48 patients with severe periodontitis admitted to Zhongshan Traditional Chinese Medicine Hospital from January 2022 to December 2022 were randomly divided into an observation group and a control group, with 24 patients in each group. All patients underwent comprehensive oral examination and clinical evaluation before surgery, including periodontal examination, periodontal pocket depth, loss of periodontal attachment, periodontal X-ray examination, and gingival bleeding index. The control group patients underwent modified periodontal flap surgery directly, while the observation group patients underwent modified periodontal flap surgery after nonsurgical periodontal treatment. Compare the treatment effectiveness and periodontal indicators between two groups of patients. Results The effective rate of treatment in the observation group was higher than that in the control group, and the difference was statistically significant (P < 0.05). Three months after operation, gingival bleeding index, periodontal pocket depth and periodontal attachment loss in the observation group were lower than those in the control group, with statistical significance (P < 0.05). Conclusion Non surgical treatment before periodontal flap surgery can significantly improve the efficacy of patients with severe periodontitis, and has a positive effect on improving periodontal indicators such as gingival bleeding index, periodontal pocket depth, and periodontal attachment loss.