When the permanent magnet synchronous motor runs at low speed, the output current is affected by the nonlinear factors of the inverter, which leads to the motor speed or output torque pulsation and can not provide efficient and stable power output. To solve the problem that the traditional motor current harmonic extraction strategy is limited by the phase delay and inaccurate extraction caused by the low-pass filter itself, and it is difficult to balance the fast response and accurate extraction suppression, a control parameter design method of reconstructing virtual polyphase motor to extract each current harmonic and suppress the harmonic current is proposed. Firstly, based on the characteristic that a polyphase motor has an independent harmonic plane, the accurate extraction strategy of the current harmonic is studied. Secondly, based on the reconstructed harmonic suppression model of control delay, the design of control parameters considering the influence of delay is studied. Finally, through the establishment of a simulation and experiment platform, it is verified that the proposed method has the effect of current harmonic suppression compared with the traditional method at low speed. Combined with the designed control parameters, the harmonic content is reduced by 94% after current harmonic suppression, which is better than the effect of 85% harmonic suppression using the traditional harmonic suppression strategy, and the goal of fast response and accurate extraction and suppression of current harmonic is realized.