Section 176 of Treatise on Cold Damage Diseases says:Cold damage disease is characterized by floating and slippery pulse,exterior heat and interior cold;and Baihu Decoction is effective for that. Many ancient physicians doubted the section and had wrong explanations.The paper believes that from the medical theory the cold here is obviously not the cold corresponding to hot,but the cold pathogen,which reflects that Zhang Zhongjing paid great attention to the medical theory.