Abstract: We propose a new chaotic image encryption algorithm based on hyperchaotic and bit substitution.The algorithm uses Hyperhenon map and Kent map, and makes the encryption process be related closely with the plaintext image's self characteristics. First, A chaotic sequence generated by Kent map is used to make image position global scrambling; Then, use Hyperhenon map to generate a chaotic sequence, and by using properties of the chaotic sequence to scramble internal bit of each pixel and pixel diffusion so that plain image information can be well hidden.The simulation results show that the algorithm can better resist statistical characterization, differential attack, and can effectively resist chosen plaintext (ciphertext) attacks, and have big key space, good encryption effect.