The invention discloses a novel two-stage air compressor comprising a housing, an air filter, an air inlet valve and a screw main machine, wherein an air filter is fixedly arranged in the inner cavityof the housing; the air inlet valve is communicated with one side of the air filter; the screw main machine is communicated with one end of the air inlet valve; a primary main machine is fixed at oneside of the screw main machine; a secondary main machine is fixed at one side of the primary main machine; a permanent magnet motor is fixed at the other side of the screw main machine; an oil-gas separator is connected at the bottom of the screw main machine through a connecting pipe; and a pressure maintaining valve is connected on the top of the oil-gas separator through a pressure sensor. Thenovel two-stage air compressor disclosed by the invention has the advantages that the design is reasonable and novel; the gas pressure generated by the two-stage compression mode is high; under the same pressure, the air compressor adopting the two-stage compression has a longer service life than an air compressor adopting one-stage compression and has less wear; the compressed air pressure is stable; and therefore, the two-stage air compressor has high practicality and is suitable for wide popularization and application.