To accurately analyze the harmonic components in the output excitation signal of the standard vibrator under low-sampling AD quantization and meet the high-precision total harmonic distortion （THD） acquisition requirements in vibration calibration. First， a low-speed sampling module for the vibration data of the standard vibrator's output excitation signal was built using the AD7606 chip. The influence of low-sampling AD quantization on the resulting THD test error of the excitation signal was analyzed experimentally. Second， an error correction method based on a least squares support vector machine （LSSVM） combined with a local outlier factor （LOF） uniform sampling was proposed. The error data caused by low-sampling AD quantization were corrected using the identified error correction model， leading to more accurate extraction of key parameters such as individual harmonics and THD. The final simulation and experimental results show that the LSSVM error correction model identified using the LOF-based uniform sampling strategy achieves higher fitting accuracy compared to conventional error correction methods， and is able to limit the error between the THD analysis results of the low-speed sampling module and the NI data acquisition card to within 0.45%.