The selectively multi-image lossless real time encryption based on notable pixels composite matrix was proposed in this paper. All the pixels of plaintexts was permutated by introduction of the Zigzag mechanism; then the image pixels was divided into important pixels and unimportant pixels by defining the pixels of interest selection mechanism, and the composite matrix was obtained by establishment of the iteration plural model. The key matrix was obtained using the singular value decomposition. Finally, the cipher was formed by constructing the diffusion function to diffuse the notable pixel composite matrix. This algorithm not only encrypted the image significant pixels, but also avoided the diffusion of non-significant pixel, which resulted in low complexity. The simulation results showed that this algorithm is of highly security, and belong to lossless encryption; comparison with other multi image encryption mechanism, the encryption/ decryption efficiency of this algorithm was higher to meet the requirement of real time transmission. Taken together, the above mentioned algorithm can simultaneously and real-time encrypt multiple images for transmission.