Abstract: In optical integration,to be coupled into waveguide is very important to light wave from free space.Through antenna resonance,light wave in free space can be coupled into waveguide.Reflect is added under antenna to reflect the transmitted wave,aiming to improve the utilization of incident light and coupling efficiency.The three dimensional finite difference time domain (3D-FDTD) method have been employed to simulate the interaction of light wave and metal structure,and to optimize structure parameters.Result shows that the coupling efficiency is increased by adding reflector,as a result of the maximum reaching 27.8 %.