Roots blower is a positive displacement blower, impeller end, fan cover. The principle is to use the two lobed rotor in the cylinder for relative motion to compress and transport the gas rotary compressor. The utility model has the advantages of simple structure and convenient manufacture. Its use in building materials, electric power, smelting, chemical and petrochemical, mining, ports, textile, medicine, paper making, aquatic products and many other fields. When the sealing device with good air tightness is used, the utility model can also be used for conveying gas outside the air, such as hydrogen, industrial oxygen, carbon monoxide, carbon dioxide, hydrogen sulfide, methane, acetylene, gas, etc..