Abstract: Aiming at the problems of data theft and privacy leakage in the process of digital image calculation, storage and transmission, a multi-image encryption method based on hyperchaotic system with variable parameters is proposed. Firstly, the state variables of one chaotic system are used to perturb the state parameters of the other chaotic system, and a hyperchaotic system with variable parameters is constructed. Secondly, the input gray image pair is reconstructed and input into SHA-512 algorithm to generate the initial key. Then, the initial key is input into the hyperchaotic system with variable parameters to generate five groups of chaotic sequences iteratively, and then the reconstructed image is transformed into a magic square to achieve the transformation of pixel positions. Finally, the S-shaped diffusion is performed on the image obtained by the magic square transformation to realize the change of the pixel value, and an approximately uniformly distributed ciphertext image is obtained. The results show that the algorithm improves the low randomness and low complexity of the traditional image encryption method, and at the same time, and improves the disorder of the ciphertext image and the ability of the encryption method to resist conventional attacks.