Abstract：In Huangdi Neijing，the clear and the turbid are often used to represent the physiology，pathology，etiology and pathogenesis of the human body，and to guide clinical treatment. This paper discusses the meaning of the clear and the turbid and their relationship with stroke，and concludes that the counterflow and disorder of the ascending and descending of the clear and the turbid is the core pathogenesis of stroke in the acute stage. This paper unprecedentedly proposes that in the acute or hyperacute stage of stroke， the key to capture the core pathogenesis of stroke is to use the clear and the turbid instead of yin and yang. It also points out that “the clear and the turbid disturbs each other”，and “turbid pathogen affects the clear”，and these are the main pathological state of stroke.