LeiFeng is one of the famous doctors in the late qing dynasty. In the treatment of cold disease, he attached great importance to the latent pathogen. The theory of latent pathogen is the earliest originated in Huang Di's Classic of Internal Medicine. After different times of doctors' research, this theory has formed different points of view. In his representative works Treatise on Seasonal Febrile Diseases, LeiFeng expounded his views to the latent pathogen from the pathogenesis, clinical feature, and so on. His main contribution to the theory lies in the induction of incidence characteristics of latent pathogen transformed from six exogenous factors.