The phase encryption and decryption of optical image in Fourier domain are studied by computer simulation. The chaotic sequence is used to construct the phase array to compress the data of decryption key to make it saving and transferring conveniently. A novel phase-ring distribution is used to make encrypted image with a rotative invariance so that the orientation of encrypted image is unconsidered during decryption. The noise can be reduced and the edges can be enhanced because this type of phase array has some functions as same as high-pass or low-pass filters. In this encryption method the ultra-low-frequency components of encrypted image in Fourier domain is more important and has a greater influence on the quality and signal-to-noise ratio of decrypted image than the high-frequency components do.