The invention provides a permanent magnet fixing method for a surface-mounted high-speed motor rotor with a permanent magnet. The method comprises the steps of firstly, carrying out cleaning and planarization treatment on the outer surface of an assembled motor rotor and then cutting carbon fiber prepreg; secondly, winding the outer surface of the motor rotor with the prepreg and strapping the motor rotor wound with the prepreg by using a wrapping strap; thirdly, wrapping the strapped motor rotor by using a ventilated felt, putting the motor rotor into a vacuum bag and vacuumizing the vacuum bag, thereby fixing the prepreg on the outer surface of the motor rotor; fourthly, heating the vacuumized motor rotor and curing the prepreg; and finally removing the vacuum bag, the ventilated felt and the wrapping strap and carrying out planarization treatment on the surface of the molded prepreg. The permanent magnet fixing method has the advantages of low cost, high efficiency and high structural strength of the motor rotor.