The invention discloses a screw-type air compressor including a machine body. A pedestal is arranged on the bottom of the machine body. A hood is arranged inside the machine body. A male rotor is installed inside the hood and is engaged with a female rotor. One end of the male rotor is connected to the hood through a bearing. A driving gear is installed on the other end of the male rotor and is engaged with a driven gear. By means of a filter core and a second air guiding pipe, air is filtered to remove dust, so that a problem of dents on the surfaces of the male and female rotors when the male and female rotors are directly contacted with dust or tiny sand can be avoided; meanwhile, by means of cooling fins on a side wall of the hood, heat dissipating efficiency of the hood is increased;by embedding a copper core in the cooling fins, heat conduction speed of the cooling fins is increased; by means of a cooling box, air entering the hood can be cooled, so that the air, when entering the hood, can directly cool the male and female rotors, thereby improving cooling effect.