A rotary compressor comprising: a casing , two ends of the casing in an axial direction having a first end wall and a second end wall respectively; an electric motor disposed in the casing and comprising a stator core and a rotor core ; and a compression mechanism disposed in the casing and located at one side of the electric motor far away from the first end wall , the compression mechanism comprising an air cylinder assembly and a main bearing , the main bearing being connected to a side end face of the cylinder assembly adjacent to the electric motor , wherein the electric motor and the compression mechanism are disposed coaxially with the casing , the stator core has a peripheral wall fixed to an inner circumferential wall of the casing , and the compression mechanism is configured to discharge a high-temperature and high-pressure refrigerant upwardly, wherein in the axial direction of the casing , the largest distance between a side end wall of the stator core adjacent to the first end wall and the first end wall is denoted by Dst; wherein in the axial direction of the casing , the smallest distance between a side end wall of the rotor core adjacent to the first end wall and a radially outermost part of a flange portion of the main bearing adjacent to the first end wall is denoted by Drt; wherein air holes are formed on and throughout the rotor core and a central axis of each air hole is parallel to a rotation axis of the rotor core ; characterized in that Dst and Drt satisfy a relationship: 0.335≤Dst/Drt≤0.838; and wherein the air holes are axisymmetrically distributed about a first diameter of the rotor core and a width D of the air hole in the first diameter direction satisfies a relationship: 0.204mm≤D≤0.480mm. a casing , two ends of the casing in an axial direction having a first end wall and a second end wall respectively; an electric motor disposed in the casing and comprising a stator core and a rotor core ; and a compression mechanism disposed in the casing and located at one side of the electric motor far away from the first end wall , the compression mechanism comprising an air cylinder assembly and a main bearing , the main bearing being connected to a side end face of the cylinder assembly adjacent to the electric motor , wherein the electric motor and the compression mechanism are disposed coaxially with the casing , the stator core has a peripheral wall fixed to an inner circumferential wall of the casing , and the compression mechanism is configured to discharge a high-temperature and high-pressure refrigerant upwardly, wherein in the axial direction of the casing , the largest distance between a side end wall of the stator core adjacent to the first end wall and the first end wall is denoted by Dst; wherein in the axial direction of the casing , the smallest distance between a side end wall of the rotor core adjacent to the first end wall and a radially outermost part of a flange portion of the main bearing adjacent to the first end wall is denoted by Drt; wherein air holes are formed on and throughout the rotor core and a central axis of each air hole is parallel to a rotation axis of the rotor core ; characterized in that Dst and Drt satisfy a relationship: 0.335≤Dst/Drt≤0.838; and wherein the air holes are axisymmetrically distributed about a first diameter of the rotor core and a width D of the air hole in the first diameter direction satisfies a relationship: 0.204mm≤D≤0.480mm. <EOS>