In order to improve the light extraction efficiency of flip-chip light-emitting diode (LED), we propose to prepare a SiO2 dielectric grating on the sapphire substrate surface and form a surface grating flip-chip LED structure. The surface grating flip-chip LED model is established by the CAD module of RSOFT software. Then, the LED module of RSOFT software is used to simulate and optimize the surface grating flip-chip LED. Simulation optimization and theoretical analysis show that, when p-GaN layer thickness hp=220 nm, n-GaN layer thickness hn=100 nm, sapphire substrate thickness hs=130 nm, grating period p=260 nm, grating thickness hg=20 nm, grating duty cycle f=0.02, the light extraction efficiency of the surface grating flip-chip LED can reach to 49.12%, compared to the best normal flip-chip LED light extraction efficiency (30.56%), the efficiency raises by 63%. The research can provide theoretical research methods for the future design of LED with high light extraction efficiency, and provide theoretical guidance for the preparation of devices.