Multimedia security is already one of the most crucial problems in information science. Specially, as the character of digital image, the traditional cipher such as DES and RSA are not suitable for being applied to encrypt the digital image. Therefore, the study of image encryption scheme attracts the interest of large researchers. Nowadays, a variety of image encryption methods have been proposed with several kinds of structures. Many of them can finish the encryption process effectively. However, most of them are only based on encryption of two phases: substitution and diffusion, which is a traditional framework. In order to achieve an exceptional encryption effect, this paper presents a novel encryption structure named as PSDIS network(Partitioning Substitution and Diffusion-Integration Substitution network). Based on this structure, a corresponding encryption algorithm is designed utilizing the generalized multidimensional Arnold cat map and PSD-IS network structure. The experimental results and their analyses demonstrate that the proposed scheme is secure and meets the requirement of image encryption.