In order to simultaneously improve the light extraction efficiency and internal quantum efficiency of GaN light emitting diodes(LEDs), GaN LEDs are integrated with quasi-symmetric optical waveguide (including grating, Ag thin layer and SiO₂ layer) and the GaN LED structure is optimized and analyzed based on the finite difference time domain (FDTD) method. The simulation results show that the surface plasma polaritons are excited by the light emitted from the active region in the Ag thin layer which produces the Purcell effect with the active region and thus the internal quantum efficiency is significantly improved. In addition, the existence of the high transmission grating makes the light extraction efficiency of LED significantly improved. Moreover, with the grating layer, the refractive index quasi-symmetrical waveguide structure is formed on both sides of the Ag thin layer, which further improves the light extraction efficiency of surface plasma polaritons and makes the uniform electric field distribution on both sides of the Ag thin layer.