A method for suppressing fluctuations in compressor speed, characterized in that the method comprises the following steps: obtaining a shaft error Δθ which reflects a deviation of an actual position of a compressor rotor from an estimated position of a compressor rotor; filtering the shaft error Δθ to obtain a corrected shaft error Δθ ' in which at least a part of fluctuation on the shaft error is eliminated and obtaining an angular velocity compensation amount P_out corresponding to the corrected shaft error Δθ'; compensating an output angular velocity Δω_PLL of a phase-locked loop regulator in a phase-locked loop for compressor control with the angular velocity compensation amount P_out to obtain a compensated angular velocity output Δω'; wherein the compensated angular velocity output Δω' = P_out + Δω_PLL; and correcting a real-time angular velocity ω1 which is used for compressor control according to the compensated angular velocity output Δω' and controlling the compressor according to the corrected real-time angular velocity ω1; wherein the step to filter the shaft error Δθ comprises: expanding the shaft error Δθ by Fourier series to obtain a function expression of the shaft error with respect to a mechanical angle θm; multiplying the function expression of the shaft error with cos ( θ mn + θ shift-Pn) and -sin ( θ mn + θ shift-Pn) respectively; extracting a d-axis component of a nth harmonic of Δθ and a q-axis component of a nth harmonic of Δθ by a low-pass filter or an integrator; θ mn is a mechanical angle of a nth harmonic and θ shift-Pn is a phase compensation angle of a nth harmonic; and eliminating a d-axis component and a q-axis component of one or more harmonics to complete a filtering process of the shaft error Δθ. obtaining a shaft error Δθ which reflects a deviation of an actual position of a compressor rotor from an estimated position of a compressor rotor; filtering the shaft error Δθ to obtain a corrected shaft error Δθ ' in which at least a part of fluctuation on the shaft error is eliminated and obtaining an angular velocity compensation amount P_out corresponding to the corrected shaft error Δθ'; compensating an output angular velocity Δω_PLL of a phase-locked loop regulator in a phase-locked loop for compressor control with the angular velocity compensation amount P_out to obtain a compensated angular velocity output Δω'; wherein the compensated angular velocity output Δω' = P_out + Δω_PLL; and correcting a real-time angular velocity ω1 which is used for compressor control according to the compensated angular velocity output Δω' and controlling the compressor according to the corrected real-time angular velocity ω1; wherein the step to filter the shaft error Δθ comprises: expanding the shaft error Δθ by Fourier series to obtain a function expression of the shaft error with respect to a mechanical angle θm; multiplying the function expression of the shaft error with cos ( θ mn + θ shift-Pn) and -sin ( θ mn + θ shift-Pn) respectively; extracting a d-axis component of a nth harmonic of Δθ and a q-axis component of a nth harmonic of Δθ by a low-pass filter or an integrator; θ mn is a mechanical angle of a nth harmonic and θ shift-Pn is a phase compensation angle of a nth harmonic; and eliminating a d-axis component and a q-axis component of one or more harmonics to complete a filtering process of the shaft error Δθ. expanding the shaft error Δθ by Fourier series to obtain a function expression of the shaft error with respect to a mechanical angle θm; multiplying the function expression of the shaft error with cos ( θ mn + θ shift-Pn) and -sin ( θ mn + θ shift-Pn) respectively; extracting a d-axis component of a nth harmonic of Δθ and a q-axis component of a nth harmonic of Δθ by a low-pass filter or an integrator; θ mn is a mechanical angle of a nth harmonic and θ shift-Pn is a phase compensation angle of a nth harmonic; and eliminating a d-axis component and a q-axis component of one or more harmonics to complete a filtering process of the shaft error Δθ.