Abstract: The article explores the common pathogenesis and transmission mechanism of exogenous febrile diseases. It points out that the invasion of external evils leads to the wei qi resisting evils, the struggle between good and evil, and the stagnation of yang qi, thus showing a series of febrile disease syndromes, and the pathogenesis is characterized by "stagnation-deficiency". The theory of "qi-blood and body-function" is used to summarize the transmission and change patterns of febrile disease syndromes, and the course of febrile diseases is summarized into two stages: qi and blood. The qi phase includes the wei phase, mainly characterized by functional disorders; the blood phase includes the nutrient phase, mainly characterized by substantial damage and accompanied by more severe functional disorders. The pathogenesis of severe exogenous febrile diseases transformation includes excessive heat stimulating blood circulation, heat inducing pericardium closure, excessive heat activating wind, the source of generation and transformation being cut off, cold-conversion of Shaoyin, and collapse of healthy qi, etc.