An electric motor rotor, comprising: a rotor body provided with a rotor bore and a plurality of magnetic steel slots surrounding the rotor bore, wherein an outer contour of the rotor body comprises a plurality of concentric arc segments in concentric with the rotor bore, wherein a central angle α of each concentric arc segment satisfies α=360/P ∗ θ, in which P represents the number of rotor poles, and 0 < θ ≤ 0.8, and a connecting line segment connecting adjacent concentric arc segments of the plurality of concentric arc segments, wherein each of the plurality of magnetic steel slots surrounding the rotor bore has an elongated shape and is perpendicular to a connecting line between a midpoint of a corresponding one of the plurality of concentric arc segments and a center of rotor bore, and each magnetic steel slot comprising one permanent magnet therein with a distance Lm between two ends of the permanent magnet satisfying L2=Lm ∗ k, in which 0.2 ≤ k ≤ 0.8, wherein the connecting line segment consists of one straight line segment connecting the adjacent concentric arc segments and, wherein the straight line segment has a central normal line being a normal line passing through a midpoint of the straight line segment and perpendicular to the straight line segment, the central normal line passing through a center of the rotor bore, and wherein two slits are formed between the magnetic steel slot and its corresponding concentric arc segment, and are spaced apart from each other, wherein the two slits are symmetrical relative to a connecting line between a midpoint of the concentric arc segment and the center of the rotor bore, and wherein respective first ends of the two slits adjacent to the concentric arc segment are inclined towards the connecting line between the midpoint of the concentric arc segment and the center of the rotor bore, such that a distance between the respective first ends of the two slits adjacent to the concentric arc segment is denoted as L1, and a distance between respective second ends of the two slits adjacent to the magnetic steel slot is denoted as L2, in which 0.5 ≤ L1/L2 ≤ 0.8, and wherein a magnetic bridge is defined between two ends of each magnetic steel slot and the connecting line segment adjacent to the ends of the magnetic steel slot, and a thickness T of the magnetic bridge has a range of 0.3mm ≤ T ≤ 1.0mm. a rotor body provided with a rotor bore and a plurality of magnetic steel slots surrounding the rotor bore, wherein an outer contour of the rotor body comprises a plurality of concentric arc segments in concentric with the rotor bore, wherein a central angle α of each concentric arc segment satisfies α=360/P ∗ θ, in which P represents the number of rotor poles, and 0 < θ ≤ 0.8, and a connecting line segment connecting adjacent concentric arc segments of the plurality of concentric arc segments, wherein each of the plurality of magnetic steel slots surrounding the rotor bore has an elongated shape and is perpendicular to a connecting line between a midpoint of a corresponding one of the plurality of concentric arc segments and a center of rotor bore, and each magnetic steel slot comprising one permanent magnet therein with a distance Lm between two ends of the permanent magnet satisfying L2=Lm ∗ k, in which 0.2 ≤ k ≤ 0.8, wherein the connecting line segment consists of one straight line segment connecting the adjacent concentric arc segments and, wherein the straight line segment has a central normal line being a normal line passing through a midpoint of the straight line segment and perpendicular to the straight line segment, the central normal line passing through a center of the rotor bore, and wherein two slits are formed between the magnetic steel slot and its corresponding concentric arc segment, and are spaced apart from each other, wherein the two slits are symmetrical relative to a connecting line between a midpoint of the concentric arc segment and the center of the rotor bore, and wherein respective first ends of the two slits adjacent to the concentric arc segment are inclined towards the connecting line between the midpoint of the concentric arc segment and the center of the rotor bore, such that a distance between the respective first ends of the two slits adjacent to the concentric arc segment is denoted as L1, and a distance between respective second ends of the two slits adjacent to the magnetic steel slot is denoted as L2, in which 0.5 ≤ L1/L2 ≤ 0.8, and wherein a magnetic bridge is defined between two ends of each magnetic steel slot and the connecting line segment adjacent to the ends of the magnetic steel slot, and a thickness T of the magnetic bridge has a range of 0.3mm ≤ T ≤ 1.0mm.