According to the voice signal conversion system and the voice signal processing method suitable for the hearing aid, the structural design is simple and reasonable, the voice signal processing effect can be improved, and the wearing comfort is improved. The system comprises a voice acquisition module, an anti-aliasing filtering module, a programmable gain amplification module, an analog-to-digital conversion module with offset compensation, a digital audio signal processing module and a voice output module which are integrated on the hearing aid and connected in sequence. The voice signal processing method based on the voice signal conversion system comprises the steps of picking up continuous analog voice signals, removing high-frequency harmonic components in the analog voice signals, adjusting the dynamic range of the voice signals, obtaining adjusted voice signals, performing analog-to-digital conversion on the adjusted voice signals, obtaining digital voice signals, and performing hearing compensation processing and digital signal algorithm processing on the digital voice signal to obtain a discrete digital signal sequence, performing digital-to-analog conversion on the discrete digital signal sequence, and outputting an analog audio signal.