YOU Zaijing,a doctor of Wumen region,and a famous expert of Treatise on Pathogenic Diseases, also made great achievements in warm diseases. He cleared the source of cold pathogenic diseases and warm diseases, distinguish the difference between them. He put forward the importance of correcting and understanding the disease nomenclature. He explained the names of warm diseases,wind-warm disonder, pestilence,damp-warm disease,warm toxin and warm malaria.He divided warm diseases into newly acquired warm disease, warm disease caused by incubating pathogens, warm disease mixed with dampness and pestilence.He used pungent and cool natured drugs and the method of regulating lung to treat wind warm diseases.In the treatment of warm toxin, he used the method of venting pathogen with cool-scattered natured drugs. In the treatment of warm disease caused by incubating pathogens,he used the method of clearing away heat, nourishing yin and venting pathogen. In the treatment of dampness-warm disease, he used the method of eliminating dampness and heat separately. In the treatment of pestilence, he took the location of disease as the core.According to the different disease locations of the pestilence, different treatment methods and prescriptions were selected.He listed five methods of treating pestilence and established a theoretical framework for the treatment of pestilence,embodying the thought of guiding the trend along the development.He put forward the theory of Six Channels directing Cold and Warm early.He tried to use the syndrome differentiation of six channels system to direct all exogenous diseases such as cold pathogenic diseases and warm diseases. He was the pioneer advocator of the cold-warm combined theory. His views on warm diseases had a profound impact on later doctors. This paper summarizes his main points, analyzes his theory, and provides inspiration for the diagnosis and treatment of warm diseases.