In order to remove the VOCs (volatile organic compounds) in civil aircraft cabin efficiently, the optical component in a new aircraft pipe line photocatalytic decontamination device is designed, simulated and optimized in this paper. In this optical component, the UVLED (ultraviolet lightemitting diode) point light sources which located at both ends of the light guide plate are transformed into an area light source for uniform illumination in the decontamination device. Limited by the configuration of the device, the light guide plate must be narrow and long, so it is a problem to have uniform optical performance. To solve this problem, reasonable optical design and simulation are conducted in this paper. In addition, dot distribution on the light guide plate is optimized according to the simulation results for better optical performance.