Recently, rhenium disselenide (ReSe₂) has become a research hotspot due to its good infrared light response and anisotropic properties. Through the salt-assisted chemical vapor deposition technology, large-area monolayer ReSe₂ films with a size of 80 microns were successfully synthesized on SiO₂/Si substrates. The morphology, spectrum, thickness and element composition of ReSe₂ films samples were analyzed by means of Raman spectroscopy (Raman), photoluminescence spectroscopy (PL), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), revealing that the as-prepared ReSe₂ films have high crystal quality. Field-effect transistor photodetectors were fabricated based on the monolayer ReSe₂ films and their photoelectric properties were systematically investigated, and the response time of millisecond level is achieved.