Dermanyssus gallinae (also known as the red mite, poultry mite, red poultry mite, roost mite and chicken mite) is an ectoparasite of poultry and other bird species. The mites cause pain, irritation, and a decrease in egg production. Red mites can survive for longer time in an empty hen house. They may serve as vectors for diseases such as Salmonellosis etc. and can also bite some species of mammals, including humans. Therefore, in present study it is significant to conduct an investigation in five chicken farms in Beijing by clinical inspection, sample collection, and pathogenic morphological observation. We identified the mites as species Dermanyssus gallinae. In addition, drug treatment and disinfection of the environment are still effective means for prevention of chicken mites.