The invention relates to a motor driving power supply for a rotary sidewall sampler. The driving power supply comprises a power factor correction unit, a voltage regulation unit, a modulation boosting unit, a filtering demodulation unit, an inverting commutation unit, a two-phase signal generation unit and a control unit, wherein the power factor correction unit performs power factor correction on a single-phase AC power signal to obtain a first DC signal; the voltage regulation unit receives a frequency setting control signal, and performs voltage regulation on the first DC signal to obtain a second DC signal; the modulation boosting unit receives a sinusoidal pulse width modulation signal, and converts a second power signal into a first high voltage low frequency waveform signal; the filtering demodulation unit filters the first high voltage low frequency waveform signal to obtain a second high voltage low frequency waveform signal; the inverting commutation unit receives a commutation driving pulse signal, and performs inverting commutation processing on the second high voltage low frequency waveform signal to obtain a low frequency sinusoidal signal; the two-phase signal generation unit performs phase output control processing on the low frequency sinusoidal signal to obtain a two-phase low frequency sinusoidal signal; and the control unit generates the frequency setting control signal, the sinusoidal pulse width modulation signal and the commutation driving pulse signal according to load current. The power supply can supply power directly by using a generator on a logger vehicle.