The etiology, pathogenesis, clinical characteristics and therapeutic methods and prescriptions of the COVID-19 were analyzed based on the diagnosis and treatment experience of nearly 100 patients with COVID-19 in Shanghai. According to the characteristics of the disease, combined with the characteristics of the climate and residents’ physique in Shanghai, it is believed that COVID-19 belong to the category of “damp pestilence” in Traditional Chinese Medicine (TCM). The cause of the disease is the invasion of damp toxin and epidemic pathogens. The location of the disease mainly lies in the lungs, diffusing to the peuro-diaphragm and triple energizers. The key of the pathogenesis is that the damp toxin and epidemic pathogens attack the lungs, pathogens stagnated in the lungs transform into heat, and damp toxin and stagnation of heat are tangled up to diffuse to the peuro-diaphragm and triple energizers, transforming into dryness and consuming fluid, exhausting qi and impairing yin. For patients who are critically diseased, pathogens may go deeper into the nutrient-blood phase and heat pathogen may enter the pericardium. The treatment should take the principle of “eliminating pathogen” as the first priority, and the key treatment method is to disperse, drain and expel so as to give the pathogens of damp toxin a way out as soon as possible. At the early stage, it is necessary to resolve dampness and dispel turbidity, to diffuse and expel, and to disperse and drain. If the damp toxin stagnates and transforms into heat, clearing the stagnated heat should be considered as a complementary treatment method. If the damp toxin transforms into dryness and consumes body fluid, protecting fluid should be of great importance. At the middle stage, it is necessary to clear the lungs and purge the fire, diffuse the lungs and unblock the bowels, dredge the peuro-diaphragm and regulate the triple energizers, with the focus on dispelling damp toxin, clearing heat toxin and resolving stasis toxin, so as to stop the disease progress and protect yin and fluid in time. In the critical period, supportive treatment should be provided and formulas for opening obstruction and preventing desertion should be prescribed for severe cases. In the recovery period, attention should be paid to clear away residual pathogens, invigorate qi and nourish yin, as well as prevention and healthcare after initial recovery. TCM focuses on eliminating toxin and pathogens as early as possible (at the primary and middle stages) to stop the progress of COVID-19, improve the symptoms of patients, and facilitate the health care and recovery.