In this paper,the preparation and optical properties of rare earth do ped molybdenum selenide (MoSe₂) vertical nanowires are studied.Using analytica lly pure molybdenum selenide powder as raw material,molybdenum selenide vertical nanowires were deposited on Si substrate by thermal evaporation method,and in- situ doping was carried out by erbium nitrate during its growth process.Atomic force microscope (AFM),X-ray diffraction (XRD),ultraviolet-visible spectrophot ometer and fluorescence spectrometer were used to study the surface morphology, crystal structure and light absorption characteristics of doped molybdenum selen ide film.It is found that doped MoSe_2nanowires have stronger crystallinity an d their length increases more than 2times.At the same time,the visible light absorption and photoluminescence intensity of doped nanowires are obviously enha nced,and the intrinsic emission of band-to-band transition of MoSe_2nanowire s at 760nm is enhanced by more than 4times.In addition,the emission from Er³⁺ ions increases at 590nm and 650nm after Er³⁺ doping,which indicates that the e mission peak increases after rare earth doping,making the spectral lines more a bundant.The above results show that rare earth doping can significantly enhance the crystallinity,light absorption and luminous efficiency of molybdenum selen ide,which can be used to prepare ultra-thin and high-efficiency optoelectronic devices such as solar cells and photodetectors.