There are many diseases that cause blood vomiting, the common ones are as follows: 1. esophageal diseases, esophageal cancer, esophageal ulcer due to frequent and violent vomiting, resulting in tearing of the lower mucosa of the esophagus or the cardia, these diseases can cause blood vomiting. 2. stomach diseases, duodenal diseases, such as gastric cancer, gastric ulcer, duodenal bulb ulcer, these diseases can cause bleeding in the stomach if they invade the blood vessels and manifest as blood vomiting. 3. liver diseases. Patients with cirrhosis of the liver who develop portal hypertension, which can lead to rupture of esophagogastric fundic varices and bleeding, can also cause thrombocytopenia, all of which can cause bleeding leading to vomiting of blood. 4, blood system diseases, such as thrombocytopenic purpura, leukemia, hemophilia, etc. If the patient appears to vomit blood should promptly go to the hospital for relevant examination, clear cause to give active treatment, the patient should be given timely blood and fluid replenishment treatment to avoid endangering the patient’s life.