If the lung tumor is close to the pleura or lung field band, a puncture biopsy is necessary to determine the pathological nature of the lung tumor. The lung tumor may be benign, or it may be tuberculosis, granuloma or fungal infection, or more likely, lung cancer, but to determine the exact pathological nature of the tumor, a puncture biopsy is required. The damage of puncture biopsy is very small, and a few patients can develop pneumothorax or even bleeding. The above complications can be avoided by mastering the technique, direction and angle of puncture, but the significance of doing puncture biopsy is much greater than the occurrence of complications. Therefore, if an occupying lesion is found on CT of the lung and is proposed to be diagnosed as a lung tumor, puncture biopsy must be done to clarify the pathological nature before the next step of treatment.