The switching current harmonics caused by pulse width modulation（PWM） leads to overheating of the drive motor in vacuum environment， which affecting the reliability of the molecular pump. The LCCR filter can effectively suppress high-frequency switching harmonics. However， the parameters of the four components in the LCCR filter have a coupled effect on the frequency characteristics， making it difficult to design accurately. To address this issue， this paper proposes a systematic design process for filter parameters. Firstly， based on double Fourier analysis， the generation mechanism and spectral characteristics of switching harmonics are analyzed. Subsequently， the relationship between the amplitude of switching current harmonics and PWM modulation is analyzed using harmonic vector method. The reasons for the significant increase in harmonic amplitude of high-frequency current under high modulation ratio are explored， highlighting the necessity of suppressing high-frequency harmonics in high-speed motors. On this basis， a parameter design method for LCCR filters is proposed， and the influence of various component parameters on the system frequency response characteristics is analyzed. The stability of the current loop after introducing the LCCR filter is verified through a bode plot. Experimental results show that using the LCCR filter designed according to the method in this paper， the total harmonic distortion （THD） of motor phase current is reduced from 35.48% to 6.50%， and the stabilized stator temperature under rated speed decreases from 68.5 ℃ to 50.5 ℃.