The invention provides a permanent magnet motor rotor capable of resisting to high temperature and a low air pressure environment. The rotor comprises a rotating shaft, a rotor support, magnetic steel, a baffle and a sheath. The rotating shaft is connected with the rotor support through multiple keys, and the baffle is fixed at two sides of the rotor support; the magnetic steel is fixed on the rotor support, and the sheath fixes the magnetic steel through interference fit; when the permanent magnet motor rotor works, when the temperature rises, no gap is arranged between the rotor support andthe rotating shaft, so that heat transfer characteristics are good, and the temperature is brought out in time. Flat keys and the rotor support are integrated into one body to present the structure ofthe inner circular teeth of the rotor support, the phenomenon of gaps due to the connection of the flat keys is avoided, and good heat conduction effect can be kept. The invention provides a structure of connection of the rotating shaft and the rotor support through multiple keys, a plurality of keyways are arranged on the rotating shaft, teeth are arranged on the rotor support so that the rotorsupport is expanded to tighten the key connection and the heat conduction performance is not decreased so as to conduct the temperature of the magnetic steel of the rotor and reduce the risk of the high-temperature demagnetization.