Multi-stage dry vacuum pump

The invention relates to the technical field of vacuum, in particular to a multi-stage dry vacuum pump which is characterized in that a driving rotor shaft and a driven rotor shaft are arranged in a main pump body, and the two ends of the driving rotor shaft and the two ends of the driven rotor shaft are mounted on a first side sealing plate and a second side sealing plate respectively; the driving shaft end of the driving rotor shaft extends into the gear box and is connected with a motor rotor shaft of the motor through a flexible coupling, the other end of the motor rotor shaft is rotationally installed at the rear end of a shell of the motor, the driving rotor shaft is sleeved with a driving gear, and the driven rotor shaft is sleeved with a driven gear meshed with the driving gear. The main pump body comprises multiple stages of cavities, a driving rotor and a driven rotor are arranged in each stage of cavity, the driving rotor in each stage of cavity is arranged on the driving rotor shaft in a sleeving