Case summary: Zhao, a 72-year-old male from Baicheng, Jilin, was diagnosed with early-stage lung cancer (stage I) after finding a tumor in the upper lobe of his left lung for 1 month. Treatment procedure: “Percutaneous percutaneous lung tumor radiofrequency ablation” was performed under CT guidance. Under the guidance of “single-use guide”, the center of the tumor was targeted (Figure 1), and the tumor was hit by one-step puncture using quasi-real-time CT-guided puncture technique, and the RF ablation electrode was opened to 2 cm, covering the whole tumor. The lung window showed that the tumor and the surrounding 1cm normal lung tissue showed hairy glass-like changes (GGO) (Figure 3), which showed the typical “straw hat sign” (Figure 4 arrow), and ablated to the safe edge to achieve the radical effect. Results: The lung tumor was completely ablated and a radical result was achieved. Adverse effects: The patient did not have any pain, cough, bleeding or other uncomfortable reactions during the operation, and the heart rate, blood oxygen and blood pressure were normal on cardiac monitoring. The NCCN and the Chinese Ministry of Health guidelines for lung cancer (2011 edition) stipulate that percutaneous radiofrequency ablation can be chosen for early stage lung cancer that cannot be operated for various reasons. Using a “single-use guide” to assist CT guidance, the center of the tumor is targeted while the needle is outside the body, and then the tumor is rapidly penetrated and hit (quasi-real-time guidance technique). When the sub-electrode of the ablation electrode needle is opened, the CT confirms that the whole tumor is covered, and the tumor tissue is heated by the radiofrequency current at 90°C for 10 minutes, which completely destroys the tumor tissue and transmits the heat to the normal lung tissue 1 cm beyond the tumor, killing the possible subclinical microscopic lesions and achieving curative effect. The inflammatory exudate density increases after the tumor and lung tissue are cauterized by heat, showing “gross glassy changes (GGO)”. The marginal manifestations vary depending on the individual response. In this case, the edges of “hairy glass-like changes” are very clear and show the “straw hat sign”, which is typical and rare, and is shown here to share the experience. Percutaneous radiofrequency ablation for early-stage lung cancer is one of the radical treatments that can replace surgery because of its precise efficacy, minimally invasive and safe.