In the thesis, we incorporate the BSDF distribution with Monte Carol ray tracing to simulate the characteristics of the optical diffuser plate, and therefore create a precise optical model of diffuser plate. First at all, we measure several important optical parameters of the diffuser plate, and accordingly we model the diffuser plate in a simulation program. Furthermore, based on the diffuser model and the precise LED model, we simulate the optical distribution of the backlight unit, where the optical efficiency and uniformity are simulated. Finally, we compare the experimental results with the simulation, and a process for designing a backlight unit based on LED lighting is proposed and demonstrated.