As image is an important way of information representation, researchers pay more and more attention on image encryption. In order to improve the performance of image encryption, a novel image encryption scheme based on a hybrid cascaded chaotic system and sectoral segmentation is proposed in this paper. Hybrid cascaded chaotic system has a larger key space, higher complexity, more sensitivity to initial conditions. Four chaotic sequences relevant to a plain image are generated by this system, which strengthen plaintext correlation and the randomness. During the scrambling process, sectoral segmentation focuses on how to extract a sequence from the disk storing data, which can not only reduce the correlation between the three components of the image, but also hide image information to a large extent. Further, a DNA algorithm is used in the diffusion process. Simulation shows that the proposed scheme can effectively resist various attacks and improve the encryption performance.