Difficulty in breathing of gastric cancer patients may be related to lung metastasis, pleural effusion and other reasons, which can be treated by surgical treatment and chemotherapy. 1. Lung metastasis: it may be formed due to the direct spread of gastric cancer through blood and lymphatic channels or planting in airway, which will cause symptoms such as dyspnea, chest pain, dry cough, bloody sputum and cyanosis, etc. It is recommended to take surgical resection of lesions for treatment, and chemotherapy can also be used for treatment. 2. Pleural effusion: pleural effusion may be formed due to metastasis of the pleura of stomach. When the amount of pleural effusion is large, symptoms such as chest tightness, shortness of breath, dyspnea and cyanosis of lips will appear, and the pleural effusion can be induced out through thoracocentesis to relieve the symptoms. Therefore, gastric cancer patients with dyspnea should go to the hospital as soon as possible to find out the cause of the disease and actively cooperate with doctors for symptomatic treatment after diagnosis.