Abstract: In order to study the digital image transmission in communication security issues,a modified color image encryption algorithm based on hyper-chaos system was put forwarded in this letter.It firstly made use of the improvement of the Logistic map to scramble the pixel value of the R,G,B of colored image,then used a hyper-chaotic system to confuse the relationship between the plain-image and the cipher-image.MALAB7.0 is used for simulation.There is no rule among the cipher-text and completely different from the original image.Simulation results indicate that,the suggested encryption algorithm of image has the advantages of large key space and high efficiency and security,and moreover,is suitable for data transmission of color image.