Objective:To investigate the effect and influencing factors of microwave ablation (MVA) in the treatment of benign thyroid nodules.Methods:The clinical data of ultrasound-guided microwave ablation for thyroid benign nodules in the Second Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine from April 2017 to April 2019 were retrospectively analyzed. At 1, 3 and 6 months after operation, conventional ultrasound examination was performed to calculate the volume reduction rate of the nodules. The nodules were divided into groups according to gender, age, nodule blood supply, nodule size, nodule nature and Hashimoto′s thyroiditis background, and the related factors influencing microwave ablation were analyzed.Results:68 patients (106 nodules) with benign thyroid nodules were treated with microwave ablation. The volume of benign thyroid nodules after the MWA treatment was significantly reduced after 1, 3, 6 months, and their nodule volume reduction ratio (VRR) were (39.7±6.1)% (1 months), (56.2±5.9)% (3 months), (70.3±5.4)% (6 months), respectively. There were significant differences in the volume reduction ratio of nodules at 1, 3 and 6 months after operation among different nodule size, nodule nature and Hashimoto′s thyroiditis background, with statistically significant difference ( P<0.05). However, there was no significant difference in the reduction ratio of nodules in different gender, age and nodule blood supply at 1, 3 and 6 months after operation ( P>0.05). Pearson correlation analysis showed that VRR was negatively correlated with ablation time per unit volume, with statistically significant difference ( P<0.05). Logistic regression analysis indicated that only nodule nature and ablation time per unit volume entered the regression equation. Conclusions:The size and nature of the nodules, Hashimoto′s thyroiditis background and ablation time per unit volume will affect the postoperative volume reduction rate.