The extraction efficiency of organic light-emitting diodes(OLED) is restrained by the high fraction of energy of the guided wave in the high-index materials(ITO/organic).By using finite difference time domain(FDTD) method,we simulated three basic structures of triangle symmetry photonic crystal slab(PCS) with hexagon lattice on the ITO structure in OLED,and analyzed the improvement of these structures in the light extraction efficiency of the OLED,and provided the optimized geometric parameters and the best basic structure,which will provide the theoretical support for designing the high performance OLED.