Abstract: This paper expounds the Jueyin disease in Treatise on Cold Diseases from the perspective of the three yin three yang and kai-he-shu theory in The Yellow Emperor's Inner Classic， and probes into application of Wumei pill when treating the Jueyin disease. It is believed that Jueyin is the time when Yin is running out while Yang is about to rise. If Yin is exhausted or Yang cannot be transformed normally， the problem of incongruity between Yin and Yang will arise， which will lead to the Jueyin disease. If the onset time of a disease accords with the Jueyin， Wumei pill can be used for treatment.