In this paper, the design of kinoforms in double-random_phase encryption method is optimized by the memory-based simulated annealing technique, which is appl ied to the simulation experiment of a binary image and an image with gray levels . The results of the experiments show that, without increasing the abundance of design, the errors caused by the quantization of phases of kinoform and key is d ecreased, and almost the same image quality as the original one is obtained as a decoded image by the proposed method.