The invention provides a pedestrian crossing voice prompt system. An optoelectronic coupler is respectively connected with a traffic light signal system and a single-chip microcomputer processor. The traffic light signal system comprises a red light state signal and a green light state signal. The red light state signal and the green light state signal are converted into signals capable of being identified by the single-chip microcomputer processor via the optoelectronic coupler, and then the signals are inputted to the single-chip microcomputer processor. A time and volume module is connected with the single-chip microcomputer processor. Time and volume information generated by the time and volume module is integrated by the single-chip microcomputer processor, and signal combination processing is performed on the red light state signal and the green light state signal so that a voice signal is generated via combination. Then the voice signal is inputted to a voice selection signal processor. Corresponding voice information is selected and subjected to power amplification by a power amplifier board and then played by a loudspeaker. Helpful information prompt can be performed for pedestrians crossing a street so that safety in crossing the street is enhanced for the pedestrians.