There are many causes of blood in spit-up, usually from the oral, respiratory and digestive tracts, and may be due to cancer. Usually, blood in spitting up is commonly caused by oral diseases such as gingivitis, periodontitis, and tongue cancer, which mostly cause bleeding from the gums due to oral mucosa breakage. In addition, bronchitis, tuberculosis and other respiratory diseases can cause hemoptysis, which can also be manifested as blood in the spit, bright red and small amount of blood; reflux esophagitis, duodenal ulcer, gastric cancer and other diseases can also lead to gastrointestinal bleeding, which is manifested as blood in the spit, and its blood is mostly dark red or coffee-colored, accompanied by epigastric pain, nausea, vomiting and other symptoms. It is recommended that the patient should consult a gastroenterologist to clarify the cause of the disease. Blood in the saliva may not necessarily indicate cancer, but it does indicate some health problems and patients should pay attention to it and adjust their work and rest, diet, etc.