 This paper proposes a new method for encrypting multiple medical images simultaneously while maintaining high levels of security. The method uses a combination of linear congruence and SHA-256 techniques to generate a unique encryption key sequence for each image. This key sequence is then used to encrypt the images individually before they are combined into a single image. Finally, the encrypted image is encoded using DNA encoding to further increase its security. Simulation experiments show that the proposed method is highly resistant to interference and can provide a high level of security. This article was authored by Ju Fengwu, Jia Luzhong, Dong Lu, and others.