Abstract: Pathogenesis and treatment methods of qi-ying fen transformation in warm diseases are explored. It is believed that warm diseases are caused by yang pathogenic factors and are most likely to damage the organs and body fluids. Body fluids, as important components of human body's healthy qi, are usually present in the lungs as lung fluids, in the stomach as stomach fluids, in the intestines as intestinal fluids, and in blood vessels as nutrient yin. During the transformation from qi fen syndrome to ying fen syndrome, visceral parenchymal damage acts as its important pathological mechanism and fluid depletion in blood vessels is an important reason for exacerbating qi-ying fen transformation. Excessive fire-toxicity, as an initial factor, promotes qi-ying fen transformation. Fluid depletion is the pathological basis for exacerbating qi-ying fen transformation. Clearing heat and protecting fluids, with sweet-flavored and cold-natured drugs to generate fluids, salty-flavored and cold-natured drugs to clear heat, and combination of sweet-flavored and bitter-flavored drugs, is an inevitable treatment method for preventing and treating qi-ying fen transformation in warm diseases, and it also has important clinical guidance value for internal miscellaneous diseases and acute severe cases.