As the image encryption based on chaos is of high security and adaptability,this paper analyzes the security of the conventional image encryption algorithms based on chaotic systems and proposes a new image encryption algorithm based on diploid Logistic and Chebyshev chaotic maps.The auxiliary and the initial secret keys based on original image,as well as the reciprocally-disordered cipher sequences alternated in subsection and generated by the diploid chaotic systems,are the kernel parts of the proposed algorithm.Both the simulated and statistical results and the security analysis show that the proposed algorithm is of excellent encryption effect and high security,with a key space being up to 255×10120.