Abstract: A method of the optical image encryption based on the frequency splitting domain and Fresnel domain is proposed, after the analysis of the fractional Fourier transform and Fresnel transform, by synthesizing the advantages of multi keys and lensless feature of the fractional Fourier transform and Fresnel transform in the optical image encryption system. The Fresnel transform and hologram technique are introduced into the optical encryption system with the fractional Fourier transform to improve the security of the original encryption system without increasing other optical elements. The theoretical analysis and computer simulation indicate that the method is feasible.