Abstract: The 2D Logistic system was applied to the digital image encryption based on the thought of the higher secrecy of chaos system.The results of analysis and simulation show that the real chaos sequence has the stronger pseudo-random, the better autocorrelation and mutual correlation characteristic.Additionally, the bigger secret-key space of the three-dimension chaos system, the stronger the algorithm can be against decryption attack.The system can increase the more encryption efficiency of the algorithm.