The invention discloses a direct-current bus voltage fluctuation sampling method based on selective harmonic elimination pulse width modulation and particularly relates to control of a three-phase alternating-current motor driving system. The method comprises steps of firstly, according to SHEPWM switch angle distribution characteristics in all kinds of different frequency division numbers, determining synchronous processing intervals; according to periodicity of bus fluctuation, using sliding prediction windows generated by a repetition predictor to predict current bus voltage waveforms in the next processing interval; and according to the predicted bus voltage waveform and the switch moment, estimating flux linkage errors in the next processing interval, and correspondingly adjusting theswitch moment so as to eliminate flux linkage errors. According to the invention, excellent harmonic characteristics of SHEPWM can be kept; sliding prediction windows are generated, so waveforms of bus voltage in the future period from the moment at any moment can be predicted; and conditions are provided for implementation of compensation.