This paper presents an improved two-dimensional logistic map. Relative to the original logistic map, the improved chaos map has better performance, e.g., larger chaotic range, higher complexity, and boosting sequence. Based on these good performances, a novel encipherment strategy is designed according to the hybrid coding of DNA and S-box algorithm. During the design of the algorithm, the primary operations include chaotic stream generation, permutation, and diffusion. The chaotic streams are constructed from the improved two-dimensional logistic map. The diffusion stage is achieved by the spatiotemporal chaos algorithm. The security test reflects that the design algorithm can effectively defend against external attacks.