Abstract：The earliest records of Wendan Decoction dates back to Ji Yan Fang（ Proved Recipes Collection），and the original prescription can be seen in Wai Tai Mi Yao （Arcane Essentials from the Imperial）. Wendan Decoction runs a long history after continuous development. The theoretical study and clinical application of Wendan Decoction in Proved Recipes Collection and San Yin Ji Yi Bing Zheng Fang Lun （Treatise on Three Categories of Pathogenic Factors） were analyzed and sorted after reading the ancient documents in Chinese Medical Classics （Version 5.0） . It found that harmonization is warming in whole recipe of Wendan Decoction， which can both simultaneously treat the gallbladder and stomach， transport pivot movement， disperse pathogens separately and discharge， and dispel pathogen and clam the healthy qi. In clinical cases，focus can be paid to resolve phlegm，calm the mind，clear heat and dissolve blood stasis based on the maximum execution of effect of Wendan Decoction and syndrome differentiation， and it should be extensively applied for various internal diseases， including insomnia， palpitation， and seasonal febrile diseases.