Chest pain during deep breathing is mainly considered to be caused by lung disease. Patients with pneumonia combined with pleurisy will cause chest pain when breathing, and the pain will be more severe when breathing deeply or changing position, mainly due to inflammatory stimulation, which stimulates the pleura and causes fibrin exudation between the dirty pleura and the wall pleura, which will rub against each other and cause pain when breathing. You need to go to the hospital for chest X-ray examination, and also need to do CT examination of the lungs. Trauma or tumor irritation to the pleura also needs to be considered, which can also cause pain. Active treatment of the primary disease is needed, as well as active anti-inflammatory treatment, and various symptomatic supportive treatments are also needed.