The causes of deep breathing chest pain are commonly found in chest wall diseases, respiratory diseases, pericarditis and gastroesophageal reflux disease. 1. Chest wall diseases: sternal fracture, costochondritis, intercostal neuritis and other diseases, deep breathing when the amplitude of the thoracic movement increases, pulling the intercostal muscles and the costal periosteum nociceptive nerve endings caused by chest pain. 2. Respiratory system diseases: ① lung infection: infection causes inflammatory mediators to stimulate alveolar peripheral nerves causing pain. ② Lung cancer: if lung cancer invades mediastinal subpleural tissues and pleura, it can cause chest pain when taking a deep breath. (iii) Pleurisy: pleurisy caused by various reasons can aggravate the friction of pleura of dirty layer and wall layer when taking deep breaths, which can also cause chest pain. 3. Pericarditis: deep breathing aggravates the friction between the dirty layer pericardium and the wall layer pericardium, causing chest pain. 4. Gastroesophageal Reflux Disease (GERD): deep breathing negative pressure in the chest cavity is relatively large, which can cause and aggravate gastric acid reflux stimulation of the esophageal mucosa and burning pain behind the sternum. Deep breathing chest pain is recommended to go to the hospital for further diagnosis and treatment.