The Total Harmonic Distortion (T.H.D.) of acceleration involved in the vibrator power amplifier combination of the low-frequency primary vibration calibration system at CMS/ITRI is higher than 2% at frequencies below 2 Hz before control. This is outside the requirement of ISO 16063–11. A waveform comparison feedback control method to reduce the T.H.D. of the vibrator is proposed. This paper describes a method of distortion reduction on a low frequency vibration standard, where a laser interferometer is used, with feedback loop control software on the calibration scheme. The vibrator signal is measured by an accelerometer located on a moving platform that is driven by the vibrator, and compared with a pure sine signal to obtain an error signal. Through multiplication of the error signal by a factor k, it is combined with the original input signal of the vibrator to reduce the T.H.D. This paper shows the experimental results at 0.8 Hz and 1 Hz. The measured T.H.D. results are both below 2%. At the same time we also evaluate the typed A standard uncertainty for accelerometer voltage sensitivity. The standard uncertainty before and after improvement is 0.154% and 0.068%, respectively.