Abstract： Through the analysis of the origin， mechanism of prescription， and usage and dosage of Fengyin Decoction， and the conclusion of modern pharmacological research of Fengyin Decoction， it is believed that Fengyin Decoction can eliminate fever， paralysis and epilepsy， and is mainly used to clear heat and extinguish wind， and tranquilize by heavy settling. Any one or two of the three syndromes of fever，paralysis and epilepsy can be treated by Fengyin Decoction according to syndrome differentiation.