The invention discloses a rotating speed ripple reduction method of a high-precision permanent-magnet synchronous motor alternating current servo system based on a repetitive controller. The method is suitable for high-precision control of a permanent-magnet synchronous motor. The method comprises the steps that steady state speed fluctuation information is acquired; a primary frequency fluctuation component and a secondary frequency fluctuation component at each given speed are obtained by fast fourier analysis; a corresponding data table of each given speed and every two frequency fluctuation components is established according to experimental data; on this basis, a current loop and a motor serve as generalized objects, and the repetitive controller is set at a speed ring for inhibiting steady state fluctuation; and a compound controller output is obtained by combining with a PI (Proportional-Integral) controller for ensuring the dynamic output performance of the system. The method is simple to realize and less in parameter adjustment, can effectively reduce the steady state fluctuation of the permanent-magnet synchronous motor alternating current servo system, achieves a purpose of improving the steady state precision of the permanent-magnet synchronous motor alternating current servo system, and satisfies an application in the field of high-performance permanent-magnet synchronous motor alternating current servos.