An application research on 365 nm ultraviolet LED used in the field of ultraviolet curing is performed, and a technical method using Fresnel lens to replace traditional cylindrical lens is suggested to realize line focusing of the light source. The design process and simulation results are provided. Based on foregone flat Fresnel lens design formulae, determination basis of fundus thickness and focus with known clear aperture diameter and focus range is deduced. The optical system includes point-focusing Fresnel lens and line-focusing Fresnel lens. The models of Fresnel lens optical system and cylindrical lens optical system are established with a tracepro software. Important indexes including energy utilization efficiency and irradiance uniformity are analyzed with ray tracing. Simulation results show that the optical system using Fresnel lens can reach the optical technological indexes on the target plane and provide higher energy utilization efficiency and irradiance uniformity.