In order to study the distribution of stray light generated by high-order diffraction of metal grids, and then quantitatively control the diffraction energy distribution of grids at the design level, and improve the detection capability of the optical system, mathematical calculation software is used to analyze the optical wavebands of metal grids with different structural forms in this paper. The diffraction characteristics are modeled and simulated discretely, and the diffraction distribution of metal grids with different structures in the optical band is simulated and calculated discretely by using the fast Fourier transform method. The results show that the normalized energy of the +1~+3 order diffraction of the periodic grid is generally at the level of -3~-2 dB, and the ring grid is not concentrated in the axial direction, and as the diffraction order increases, the diffraction energy drops faster than square grids. The random grid has an almost completely uniform diffraction distribution, and the high-order normalized diffraction energy can be controlled at -6~-5 dB, which is much lower than that of the periodic grid. It can be used in the imaging system to reduce the stray light caused by the diffraction of the grid. The homogenization can reduce background noise and improve image quality.