Designed a one-dimensional photonic lattice in LiNbO₃∶Fe crystals by Fourier transform and measured the diffraction efficiency by power detector.Change the hole number of the amplitude mask and determine the photonic lattice's band-gap.When the hole number is five,the photonic crystal lattice has the most wide band and.The diffraction efficiency of grid work is the highest.If the hole number of the mask is increased from two to five,the number of diffraction light will increase from one to four,making the single Bragg diffraction angle increase for multiple,equivalent to increase the Bragg bandwidth.The writen photon lattice theory model is simulated by mathematica numerical simulation.The band-gap broadening is explained successfully in theory.