The invention provides a high-speed permanent magnet synchronous motor control method based on a modular multilevel converter. According to the method, a high-speed permanent magnet synchronous motor is driven by using the modular multilevel converter, the driving signals of the modular multilevel converter are obtained by using carrier phase shifting PWM modulation, frequency-doubled and frequency-quadrupled negative sequence rotating coordinate transformation is performed on the second harmonic component and the quadruple harmonic component of the internal circulation between the internal bridge arms of the modular multilevel converter, a circulation model under the dq coordinates is established, and AC circulation is decomposed into DC components through circulation suppression control and the DC components are respectively suppressed; and the stability of the bus voltage of the modular multilevel converter is maintained through DC bus voltage control. Extension can be performed according to the occasion requirements and the device specification requirements can be reduced, harmonic waves can be reduced, the main components in the internal circulation of the modular multilevel converter can be eliminated, the fluctuation range of submodule capacitance voltage can be reduced and the system loss can be reduced so that stable operation of the high-speed permanent magnet synchronous motor under multilevel driving can be realized.