In order to effectively simplify the preparation process and reduce the preparation difficulty of surface grating coupler, a highly efficient silicon nitride surface grating coupler compatible with complementary metal oxide semiconductor(CMOS) technology is designed. The coupler structure is modeled, optimized and simulated using two-dimensional finite difference time domain(2D-FDTD) algorithm. The spectral characteristics of couplers with different structures are calculated and compared. The research results show that the designed silicon nitride surface grating coupler on the standard silicon on insulator(SOI) wafer, with the help of CMOS back channel process, has a maximum coupling efficiency of - 3.36 dB and a bandwidth of -3 dB of 101 nm near the communication wavelength of 1550 nm.