A multispectral silicon-based photodetector structure with stacked PN junctions is proposed in this study. The substrate layer of the proposed photodetector consists of four vertically stacked PN junction structures that contain four photodiodes. The designed structure achieves quantum efficiency of up to 70% and a response time of 5.1 × 10-8 s. The proposed photodetector has a simple structure, and the vertically stacked PN junction structure not only reduces the phenomenon of color aliasing, but also achieves multispectral absorption over the range from ultraviolet to visible light with high response speeds, which provides an effective way to perform high-quality imaging.