Rotor mass imbalance and sensor runout generate harmonic currents in magnetic bearing systems, causing multi-frequency vibrations. These vibrations can significantly degrade motor operational efficiency and accelerate bearing wear. Repetitive control (RC) is an effective method for suppressing harmonic currents. However, the conventional RC (CRC) has limited resonant bandwidth and gain. When the motor speed frequency fluctuates, the performance of harmonic current suppression decreases. A feedforward fractional RC (FFRC) is proposed in magnetic bearing systems. Compared to the CRC, the improved RC with a feedforward channel has wider resonant bandwidth, higher repetitive gain, and better robustness to frequency fluctuation at the target frequency. Additionally, the incorporation of fractional-order delay filters has further improved the suppression accuracy of RC. The stability of this method is proven, and simulation results demonstrate its effectiveness.