Abstract This thesis is to explore the optical simulation for high power LED for lighting modules. Microstructures are laid out on lightguide plate surface to generate uniform illumination and reduce the LED number being used. High power LED with 1 W per chip was used for the lighting module simulation. Tapered post microstructures were used to laid out on a lightguide plate surface with 160 mm long, 35 mm wide, and 8 mm thick. Twelve high power LEDs were arranged in two rows in parallel. The obtained simulation results showed the average brightness up to 90%, the minimum brightness can reach at least 3628.05 lux. It proves that such high power LEDs lighting modules are feasible for lighting applications.