A motor permanent magnet fixing device solves the problem that in the prior art, a permanent magnet in a permanent magnet motor can easily fall off and comprises permanent magnets, a rotor support and a fixing piece. The rotor support and the fixing piece fix the permanent magnets. The motor permanent magnet fixing device is characterized in that the fixing piece comprises a non-permeability fixing block and a non-permeability inner hexagon bolt, each permanent magnet is provided with a locating slope, the non-permeability fixing block is provided with a slope face and a limiting face respectively, the length of the slope face is the same as the length of the locating slope of each permanent magnet, the threads of the bolt penetrate through a through hole of the rotor support and are connected with a thread hole of the non-permeability fixing block, the slope face of the non-permeability fixing block is matched with the locating slope of the permanent slope in inclined angle, tight contacting is achieved, and the non-permeability fixing block is used for fixing each permanent magnet on the rotor support. The motor permanent magnet fixing device is simple in structure, reasonable in design, easy to manufacture and capable of achieving fixing of the permanent magnets in a motor under any air gap size, the permanent magnets are evenly distributed and can be effectively prevented from falling off, mounting efficiency and permanent magnet using rate are improved, and permanent magnet materials are saved.