The clinical manifestation of vomiting blood often occurs in patients with advanced cancer, and the causes of vomiting blood are considered to be as follows: 1. Liver metastasis often occurs in advanced cancer, and liver metastasis damages the liver function, and the patients will suffer from the lack of coagulation factors or the decline of platelets, and then they will suffer from upper gastrointestinal hemorrhage, which will be clinically manifested as vomiting blood and black stool. Second, patients with advanced cancer often suffer from coagulation disorder, and many of them will suffer from disseminated intravascular coagulation, which will lead to upper gastrointestinal bleeding, manifested as vomiting blood. Third, patients with advanced cancer often suffer from liver function damage, and after patients develop liver cirrhosis, they will suffer from esophagogastric fundus vein varices, and clinically, they will suffer from upper gastrointestinal hemorrhage, which can be manifested as vomiting blood and black stool.