There are many reasons for vomiting blood in gastric cancer, among which there are two main reasons: firstly, it is caused by the growth of tumor cells, such as the necrosis of tumor cells due to the lack of blood supply to blood vessels, or the rupture of blood vessel walls due to the direct damage of tumor cells, which is the first reason. Secondly, bleeding caused by the application of drugs, such as chemotherapy drugs, can lead to erosion, ulceration and bleeding of gastric mucosa, which can also lead to bleeding of stomach. Of course, there are other reasons, such as abnormal coagulation function when the patient has low coagulation factor, which can also lead to bleeding from stomach cancer. After stomach bleeding, we should actively conduct examination, such as gastroscopy. Of course, we can send vomit or stool to confirm the diagnosis. If the vomit and stool are positive for occult blood, the diagnosis of gastrointestinal bleeding can be made clearly, and of course, the possibility of stomach is more likely to be considered with the patient’s medical history. Gastroscopy is very clear and intuitive to diagnose gastric bleeding and has certain therapeutic effects, but it must be done carefully when acute bleeding occurs. After bleeding from gastric cancer, patients should not be nervous, they should be calm, spit out the blood, and then go to hospital urgently for relevant treatment.