The invention relates to the field of motor assembly, in particular to an assembly method of a low-center, large-power, high-speed and high-voltage motor. The assembly method comprises the following steps of arranging a bottom leg fixing disc below a bottom leg plate of a wire embedment stator; performing mirror processing on a rotor bearing guard; performing dynamic balancing on a motor rotor; disassembling the bottom leg fixing disc, enabling the wire embedment stator to penetrate through the motor rotor, installing sliding bearings at two ends, measuring and adjusting an air gap value between the wire embedment stator and the rotor, and effectively locking the wire embedment stator; disassembling shaft tiles of the sliding bearings at the two ends, and researching the shaft tiles; opening oil bags in an oil inlet surface and an oil outlet surface of a lower tile, and trimming a contact angle between the shaft tiles and shaft necks; assembling the shaft tiles, and detecting whether oil is leaked or not; completing wiring operation outside the motor, arranging a sealing piece and a cooler, performing test, and performing spot welding and fixing on a fixed screw and a positioning pin after test is qualified. By the assembly method, the motor vibration can be reduced, the temperature rising of the bearing is reduced, the motor noise is reduced, and the service lifetime of the motor is prolonged.