Abstract: In order to achieve effective protection of the color image information,a new color image encryption algorithm is proposed based on several rounds of proliferation.Firstly,the chaotic sequences generated by‘Lorenz′ chaotic system and‘Chen′chaotic system are improved to get two groups of different chaotic sequences.Then,the pixels′positions of the image are scrambled by improved‘Lorenz′chaotic sequences.Finally,by using both of the two groups of improved chaotic sequences and the distribution of pixels in the color image,we change the pixels′ values of the scrambled image through several rounds of proliferation and get the ciphered image.Theoretical analysis and simulation results show that this algorithm with a sufficiently large key space not only can perfectly resist the ciphertext attack and differential attack,but also is excellent against chosen plaintext attack and statistical attack,which can be widely used in secure communication of multimedia data.