长期以来,建立传染病模型来描述传染病的传染过程，分析受感染人数变化规律，预报传染病的高潮的到来等等，一直是各国专家和官员关注的课题,这里我们介绍几个传染病模型及分析。这里我们介绍三种模型，分别为SI模型、SIS模型、SIR模型(For a long time, the establishment of an infectious disease model to describe the infectious disease process, the analysis of the change of the number of infected people, the forecast of the arrival of the climax of infectious diseases, and so on, has always been a subject of attention of experts and officials of various countries. Here we introduce several infectious diseases model and analysis. Here we introduce three models, namely SI model, SIS model and SIR model.)