For non-small cell lung cancer, which currently has poor treatment outcomes and high mortality rates, the clinical use of EGFR-TKI-targeted drugs has brought a new light to patients. Patients with good treatment outcomes tend to take the drugs for a longer period of time, some even lasting up to 3 or 4 years. Therefore, during such a long treatment process and observation and follow-up, many problems have been identified. When there is a change in the disease, it should be accurately determined whether it is caused by resistance to the targeted drug, because it will be related to the question of whether to change the treatment strategy or not. 1. Pleural effusion In short, pleural effusion is the accumulation of fluid in the chest cavity that should not be there under normal circumstances. There are two cases: 1) Malignant pleural effusion is already present at the time of diagnosis, and the pleural fluid is repeated afterwards. 2) Pleural fluid appears during the course of targeted drug therapy. Experience: It cannot be casually judged as target drug resistance. At this time, local treatment of pleural fluid should be carried out as soon as possible: drainage of pleural fluid, followed by injection of pleural adhesions. Review chest CT to observe and measure changes in the size of major lesions. If the size of measurable lesions in the lung is more stable than before, then targeted drug therapy should be continued. It has been proved that many similar patients have their pleural fluid under control after local treatment, and continue to take targeted drugs for systemic treatment, and their condition is stable or further improved. 2, interstitial pneumonia Definition of interstitial pneumonia: It is a general term for a group of different classes of diseases constituting a clinicopathological entity with diffuse lung parenchyma, alveolitis and interstitial fibrosis as the basic pathological changes and active dyspnea, diffuse shadowing on chest CT, restrictive ventilation disorders, reduced diffusion function and hypoxemia as clinical manifestations. Secondary infection may be accompanied by mucus thick sputum, with significant wasting, weakness, anorexia, arthralgia of the extremities and other systemic symptoms, and fever in the acute phase. When patients develop unexplained chest tightness and shortness of breath during targeted drug therapy, chest CT should be examined as soon as possible. Experience: If chest CT suggests a large diffuse patchy shadow, the possibility of interstitial pneumonia should be alerted. Give the patient anti-inflammatory and intravenous hormone treatment at the same time. When the patient’s shortness of breath improved, hormone reduction maintenance therapy was given for about 2 months. Targeted drugs cannot be discontinued easily, and the dose can be reduced by half, subject to the specific dose that the patient can tolerate. Therefore, the individualized treatment of targeted drugs must be advocated: because in the specific treatment process, patients have different efficacy, different side effects and complications, and different tolerance to the drug game. In conclusion, in the process of targeted drug treatment, patients should be closely observed and followed up, and relevant experience should be continuously summarized in order to maximize the power of targeted drugs and benefit patients to the greatest extent.