Abstract: Objective To explore the efficacy and safety of microwave ablation in the treatment of thyroid adenoma under ultrasound guidance in clinic. Methods In this retrospective study，clinical data of 74 cases of thyroid adenoma undergoing ultrasound-guided microwave ablation were collected from July 2014 to July 2016. The volumetric reduction of adenoma and changes of thyroid function including triiodothyronine，thyroxine，free three iodine glycine，free thyroxine and thyroid-stimulating hormone as well as post-operative complications were analyzed. Results Under ultrasound guidance, 104 thyroid nodules were ablated by microwave. All patients recovered well postoperatively and no complication occurred except for 1 case with mild local cervical hematoma. No thyroid adenoma recurred in 74 cases. The loss of volume rates were（11.73±37.21）％，（28.71±26.72）％，（53.33±38.24）％，（78.56±15.31）％ and （94.28±4.54）％ at 1-，3-，6-，12-and 24-month after operation，respectively. The postoperative changes in serum thyroidrelated hormone levels were not statistically significant when compared with the preoperative ones. Conclusion Ultrasoundguided microwave ablation was safe for thyroid adenoma with the advantages of less trauma and quick recovery. Moreover，it has satisfying cosmetic effect，worthy of clinical promotion.