In light of the limitations and locality problems of the bit permutation process in existing bit-level encryption algorithms, a novel algorithm for self-adaptive diffusion and combined global scrambling was proposed. In the diffusion phase, the reorganization and subsequent scrambling process of bit planes is performed randomly, so that the scrambling process is not limited to just some bit planes, and we achieve the effect of global scrambling. The algorithm employed several chaotic mapping systems, allowing permutation and diffusion operations to be implemented simultaneously. To increase sensitivity to plain images and effectively resist attacks, the self-adaptive process of bit planes was added, thereby further modifying the original image data based on given rules. Simulation results demonstrate that the proposed scheme is sensitive to plain images and keys, and can resist Chosen-Plaintext Attack effectively. The cipher image has uniform pixel distribution and good image encryption.