Metal halide salts have attracted widespread attention because of their good physical and chemical properties. In this study, lead‐free copper halide salt CsCuCl3 single crystals and photodetectors were prepared. According to the single crystal diffraction data, the CsCuCl3 single crystal has a hexagonal structure with P6522 (179) space group (7.2399 × 7.2399 × 18.3096 Å, 90.000 × 90.000 × 120.000). The crystal structure along the z‐axis is a double‐stranded helix structure. To the best of our knowledge, this is the first study on CsCuCl3 for optoelectronic applications. The CsCuCl3 photodetector exhibits high light response, sensitivity, and selectivity under 369 nm ultraviolet light and invalid response for visible light (511 nm). The device based on CsCuCl3 is highly selective for ultraviolet light (2.43 µA/mW) and feature high anti‐interference of visible light (0.0119 µA/mW). The device has the strongest selectivity at 369 nm light, which is 200 times higher than that at 511 nm. The results will be of interest for applications in photodetectors, LEDs, devices, and metal halide salts.