Radiofrequency ablation is a treatment method that uses radiofrequency to produce high temperature thermal effect to kill tumor cells. For lesions less than 3 cm in the liver, it can completely kill tumor cells, achieve local radical treatment, and achieve the same effect as surgical resection. It is more frequently used for primary liver cancer, lung cancer, or other malignant tumors metastasized to the liver. The following is a case of a patient with liver metastasis after radical breast cancer surgery who received radiofrequency ablation of liver metastatic lesions. The patient was a 58-year-old female who had undergone “radical endometrial cancer surgery” in March 2014 and had no family history of tumor. CT indicated that the right breast was changed mostly due to breast cancer with ipsilateral axillary and supraclavicular lymph node metastasis. Postoperative pathological findings: invasive ductal carcinoma and lymph node metastasis. After two postoperative chemotherapies, he developed II° myelosuppression. In July, a left lobe liver mass was found on CT of the chest and abdomen, which was considered to be a metastasis. In early August, she underwent “ultrasound-guided radiofrequency ablation of breast cancer liver metastases” under general anesthesia in our department, and biopsy was taken during the operation to confirm the breast cancer liver metastases. He was discharged from the hospital in mid-August after symptomatic treatment with anti-infection and rehydration, and developed a fever of 39.2℃ after radiofrequency surgery. Image description (a): The above is the patient’s preoperative enhanced CT, which shows a 5.2cm*4.3cm*4.6cm occupancy in the left lobe of the liver with clear border, and the intraoperative puncture biopsy confirmed metastatic cancer tissue, mostly of breast origin. Picture caption (II): The above is the patient’s follow-up review of enhanced CT 2 months after surgery: the liver metastatic lesion is slightly smaller compared with the preoperative one, but the boundary of the lesion is clearer, and the lesion is uniformly hypodense change within the lesion, and the blood supply is obviously reduced. Experience summary: At present, it is believed that radiofrequency ablation can achieve complete ablation for single small hepatocellular carcinoma (mass less than 3cm), and for 5cm tumor, it can also achieve satisfactory ablation effect and can be the first choice of treatment. Radiofrequency thermal ablation takes advantage of the heat dissipation difference of tumor, which makes the temperature of tumor tissue higher than its adjacent normal tissue. The bio-thermal effect of RF can not only kill tumor cells directly by high heat, but also destroy tumor blood vessels to achieve the effect of blocking tumor blood supply, change PH value and hormone level in tumor, making tumor cells in an unsuitable environment for survival. In conclusion, radiofrequency ablation is a breakthrough in the treatment of malignant tumors.