Hospital sewage refers to the sewage discharged from hospitals (general hospitals, specialized hospitals and other types of hospitals, blood stations) to the natural environment or urban pipelines. The water quality varies with the nature, scale and location of different hospitals. The main pollutants in hospital sewage are pathogens (parasite eggs, pathogenic bacteria, viruses, etc.). Organic matter, floating matter and suspended matter, radioactive pollutants, etc. The total number of bacteria in raw sewage without treatment exceeds 108/ml. The sources and components of hospital sewage are complex, including pathogenic microorganisms, toxic and harmful physical and chemical pollutants, radioactive pollution, etc., It is characterized by space pollution, acute infection and latent infection. Without effective treatment, it will become an important way of disease transmission and seriously pollute the environment.