Abstract: Objective To study the therapeutic effect of ultrasound（US）-guided percutaneous cooled-tip microwave ablation（MW） on adrenal tumor. Methods Fourteen consecutive patients with 16 lesions were treated with US-guided percutaneous cooled-tip MW ablation.Its therapeutic effect was evaluated with US contrast examination and enhanced MRI/CT,etc. Results Of the 16 lesions that underwent US-guided percutaneous cooled-tip MW ablation with no severe complications,15 were completely ablated,1 with a large diameter was necrosized after 4 times of ablation.During the 27.3-month follow-up period（mean 6-62 months）,local progress was found in 1 lesion 27 months after operation.Among the 10 patients with malignant tumors,there were 9 survival after 1 year and 8 survival after 3 years. Conclusion US-guided percutaneous cooled-tip MW ablation is a safe and effective procedure for adrenal tumor with minimal invasion.