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.