Abstract: In order to accelerate the transition to new from old economic engines and build a strong modern agricultural country, light conversion agricultural film has been regarded as one of the important research directions in the field of "optical agriculture". The light conversion agents must have good weather resistance and excellent light conversion characteristics to fabricate the light conversion agricultural film. However, the existing light conversion agents have the problems of single emission spectrum and narrow emission range, which leads to the poor matching between the emission spectrum of light conversion agents and the absorption spectrum of plant photosynthesis, and seriously restricts the development of light conversion agricultural film. In this paper, a kind of organic complex (light conversion agents) doped with a variety of rare earth ions (Sm³⁺, Eu³⁺, and Y³⁺) were synthesized by use salicylic acid and o-phenanthroline as ligands. The results show that the fluorescence spectra of this kind of light conversion agents are significantly broadened by the incorporation of Sm³⁺. A light conversion agricultural film with the function of converting ultraviolet light to red light was prepared by mixing the synthesized light conversion agent into ethylene-1-hexene copolymer (PO) film by blow molding. The composition and structure of the light conversion agents were determined by FTIR and XPS. At the same time, the thermal stability and optical properties of light conversion agents and light conversion agricultural film were characterized by TGA55 and steady state and transient state fluorescence spectrometer (FLS920). The test results show that the synthesized light conversion agents can absorb ultraviolet light (λ=250-400 nm) and emits red light (λ=610-660 nm). The spectral property is highly matched with the absorption spectrum of plant photosynthesis in the red light region, and the light conversion agricultural film prepared with this kind of light conversion agents still maintains good luminescence performance, which will be conducive to the popularization and application of light conversion agents in the field of agricultural film. This study provides a practical method to broaden the fluorescence emission range of light conversion agents and improve the matching with the absorption spectrum of plant photosynthesis in the red band. The light conversion agents are successfully applied to the preparation of light conversion agricultural film, which achieve the purpose of converting ultraviolet light into red light.