Roots blower with three blades is a double impeller synchronous compressor. Each trilobal rotor is supported by two bearings, and the relative positions of the two rotors are kept constant by a pair of synchronous gears. It is the choice of clean air, clean gas and other inert gases, special gas industry and high pressure working conditions. In view of the above characteristics, Roots blower can be widely used in metallurgy, chemical industry, fertilizer, petrochemical, instrumentation, building materials and other industries.