1.Principle: Microwave antenna is used to introduce high frequency electromagnetic field into liver cancer tumor body (usually used frequency 2450, 915MHz, output power 20～80W). Under the action of microwave field around the antenna, the molecules and ions of the dielectric in the tissue move back and forth with the continuous change of high frequency electromagnetic field, so that the local temperature is raised by 65～100℃ after the friction and collision between the points and ions and the heat energy is generated. Tumor tissues contain more water than normal tissues, and the water molecules run at high speed with the microwaves issued by microwave electrodes inserted inside the tumor. This high speed operation causes mutual collision and friction between water molecules, which generates a large amount of heat energy in a short period of time, causing rapid heating of tumor local tissues, thus causing coagulation and necrosis of tumor tissues without necrosis of surrounding tissues, in order to achieve the treatment purpose. In addition, the solidified tumor tissue can stimulate the host to produce anti-tumor immunity, so that the host’s ability to resist the attack of tumor cells is obviously enhanced. 2. Characteristics: Microwave ablation (MWA) is currently one of the most advanced and relatively safe techniques used in clinical general surgery to treat tumor diseases. It utilizes the characteristics of ultrasound such as clear image, non-invasive and non-radiation and real-time direct monitoring, and uses an extra fine microwave needle of only 0.88mm to puncture into the tumor through the skin, generating high temperature above 60℃ in the tumor ablation tissue area, causing coagulation, dehydration and necrosis of the lesion tissue, thus achieving the treatment purpose. Microwave ablation treatment has the advantages of small trauma, safe and reliable, simple operation, reliable efficacy and low cost, which can be the first choice of tumor treatment. (1) Indications and contraindications: (1) Indications: mainly applicable to patients with early stage liver cancer who are not suitable for surgical treatment (including those who cannot be surgically resected, difficult to be surgically resected or cannot tolerate surgery) with single tumor diameter ≤ 125px and the number of multiple tumors not more than 3, maximum diameter ≤ 75px and no vascular, hepatobiliary cancer embolus or extrahepatic metastases, and the distance of the tumor from the hepatic portal or gastrointestinal tract is at least 5ram. Contraindications: a. Severe cardiac, pulmonary, hepatic and renal dysfunction. b.Diffuse lesions. c.Severe bleeding and coagulation abnormalities. 4.Common complications: Minor complications include fever, pain, reactive pleural effusion, small amount of intrapulmonary hemorrhage or pneumothorax, cholecystitis, skin burns, etc., which can usually subside after symptomatic treatment. Serious complications mainly include abscess, bile duct injury, liver lobe or segmental infarction, tension pneumothorax, massive intrapulmonary hemorrhage, bile heart reflex, and needle tract implantation, which have a low incidence. The incidence of major complications is 2.6%. 5, clinical treatment advantages: microwave ablation multiple microwave energy sources can be applied simultaneously, tissue heating is not affected and constrained by resistance and conductivity, electromagnetic waves can be used in a shorter period of time to make the tissue temperature higher. The energy density of electromagnetic waves generated by microwave can reach 50px around the electrode, thus the microwave has the potential to ablate the blood vessels around the target tissue and produce a wider ablation range. Microwave ablation has an automatic temperature measurement system and the single ablation time PMCT is generally 5-20 min. One treatment time only takes about 15 minutes. Microwave clinical use is wide, not only for liver cancer treatment, but also for lung cancer, breast cancer, pancreatic cancer, prostate cancer, bone cancer, uterine fibroids and other solid tumors; can be widely combined with other treatments, such as transhepatic artery embolization chemotherapy (TACE) will help strengthen the effective control of microwave ablation of tumors and expand its indications. 6. Domestic scholars treated cases: Dong Baowei et al. treated 275 nodules of 216 patients with primary hepatocellular carcinoma ≤ 5.0 cm in diameter with PMCT. 95.64% (263/275) of the tumors were completely inactivated, and the cumulative survival rates of patients at 1, 2, 3, 4 and 5 years were 94.87%, 88.81%, 80.44%, 74.97% and 68.63%. Taken together, domestic and international reports show that PMCT has achieved satisfactory near-term and long-term clinical efficacy in the treatment of small hepatocellular carcinoma.