Based on the classical literature of traditional Chinese medicine (TCM) and reflections on clinical practice, we intend to explain the etiology, pathogenesis, law of transmission and change, as well as therapeutic prescriptions of coronavirus disease 2019 (hereinafter referred to as COVID-19) based on the theory of “damp epidemic”. We reckon that COVID-19 is caused by the endogenous damp toxin and exogenous epidemic pathogens, which interact with each other and contribute to the disease together; COVID-19 pandemic not only follows the law of transmission and change of Wei-Qi-Ying-Xue, but also shows the transmission and change process within triple energizers.Besides, we also put forward clinical suggestions for the TCM diagnosis and treatment of COVID-19 through reviewing, organizing and summarizing syndromes, treatment principles and methods, prescriptions and herbal medicines of “damp epidemic” in relevant TCM classics.