A novel 1D/1D nanocomposite-based photodetector is successfully fabricated from high-crystalline ZnS/ZnO biaxial nanobelts for the first time. Optimized performance of the ZnS/ZnO nanobelt photodetector is much better than that of pure ZnS or ZnO nanostructures, with a wide-range UV-A light photoresponse, high sensitivity, and very fast response speed.