Abstract: Etching diffraction grating (EDG), one of the most critical components, can achieve wavelength division multiplex (WDM) function and realize on-chip optical interconnection. In order to realize 4-channel EDG with the wavelength spacing of 20nm at 1310nm wavelength, Kirchhoff scalar diffraction theory was used for theory design and simulation verification. To further improve the reflection efficiency and decrease the insertion loss, Bragg reflection gratings were designed to replace the normal etched facets. Multimode interference (MMI) coupler was also introduced at input waveguide for flat-top frequency response. The simulation results demonstrate the reflection efficiency of grating reflective surface is up to 85% and 1dB bandwidth is up to 12nm. The designed EDG has a significant effect on improving system stability, increasing transmission distance and capacity, and reducing system cost. The design can meet the practical application requirements of optical interconnection system.