The piezo-phototronic effect is about the use of the inner crystal piezoelectric potential to tune/control charge carrier generation, separation, transport and/or recombination in optoelectronic devices. In this paper, a theoretical model for describing the characteristics of a metal-nanowire-metal structured piezophototronic photodetector is constructed. Numerical simulations fit well to the experimental results of a CdS and ZnO nanowire based visible and UV detector, respectively.