The clinical experience of treating an elderly patient with severe coronavirus disease 2019 (COVID-19) from the angle of treating damp-warm disease was introduced. In the early stage the pathogenic factors were in the pleuro-diaphragmatic interspace; in the advanced stage the damp pathogenic factor obstructed the lung; in the severe stage the pathogenic factors entered the nutrient-blood phase and in the recovery stage the residual heat gradually receded. Under the routine treatment of western medicine, the simultaneous treatment with Dayuan decoction and Sanren decoction based on Chinese medicine pattern identification is helpful to improve the clinical curative effect by clearing heat, removing dampness and expelling pathogenic factors from the pleuro-diaphragmatic interspace.