Abstract: We design a type of environment-protecting circulation range hood.Its innovative design enables the air purified by three-level filtering to circulate indoors directly.The design consists of two key technologies: 1) the first-level filter uses the swirl-separation technology,which separates gas-solid and gas-liquid with tangential inlet and cone body;2) the second-level filtering carries out centrifuge filtering with g the filtering cloth that rotates with an impeller,thus effectively solving the problems that the circulation filter gets dirty and is hard to clean and has poor ventilation.The circulation range hood can be used not only in kitchen but also in other sealing oil mist environments.Without flue,it reduces construction costs and carbon and conserves energy.