Air filter with double-layer air filtering unit

The utility model discloses an air filter with a double-layer air filter unit, which comprises a first filter cartridge and a second filter cartridge, a first filter element is filled in the first filter cartridge, a second filter element is filled in the second filter cartridge, an air guide pipe is arranged on the outer side of the first filter cartridge, the air guide pipe is fixed on the inner side surface of the second filter cartridge, and the air guide pipe is fixed on the inner side surface of the second filter cartridge. An air inlet pipe is arranged on the inner side surface of the lower end of the first filter cartridge, a first exhaust pipe is arranged on the upper surface of the air guide pipe, a second exhaust pipe is fixed to the inner side of the second filter cartridge and communicates with the first exhaust pipe, and an air cylinder is fixed to the outer surface of the lower end of the air guide pipe; by means of the design of the two sets of filter elements, the air cylinder is matched with