External balance type screw vacuum pump

The invention belongs to the technical field of dry type vacuum pumps and particularly relates to an external balance type screw vacuum pump. According to the technical scheme, the external balance type screw vacuum pump comprises a motor, a pump body, a second gearbox, a speed-increasing gear pair, a synchronous gear pair, a driving rotor and a driven rotor. The pump body is provided with a first gearbox. The motor and the second gearbox are arranged at the two ends of the pump body. The driving rotor and the driven rotor are arranged in the pump body. The speed-increasing gear pair and the synchronous gear pair are installed at the two ends of the driving rotor and the driven rotor. The speed-increasing gear pair is arranged inside the fist gearbox. The synchronous gear pair is arranged in the second gearbox. The external balance type screw vacuum pump aims to improve the axial stress balance and achieve flow zero loss; the gears are arranged on the two sides, the transition shaft connection manner is adopt