The reasons why the morning spit is yellow may be: i. Suffering from certain liver diseases, which can lead to poor bile secretion and cause the morning spit to be yellow, such as acute and chronic hepatitis of various types (alcoholic hepatitis, viral hepatitis, pharmaceutical hepatitis, etc.), primary cirrhosis of the liver due to various causes, primary or secondary liver cancer; ii. Biliary system diseases can also cause the morning spit to be yellow, such as cholecystitis, cholangitis, gallbladder stones, bile duct stones, gallbladder cancer, bile duct cancer, primary biliary cholecystitis and other diseases that lead to poor bile drainage in the biliary system; third, pancreatic-related diseases can also have this clinical manifestation, such as pancreatitis, pancreatic cysts, pancreatic cancer and other diseases.