Abstract: For advanced the chaotic array complexity and random-like，firstly，this paper improves the Liu chaotic sequences，which makes the chaotic sequences have the ideal random characteristic property.Then the image is encrypted based on the improved Liu chaotic system sequences，and a new image encryption algorithm is proposed.The experiment results show that the algorithm has stronger resistance for the exhaustion attack，count attack and known-plaintext attack，and it is of high security.

摘要： 为了提高混沌序列的复杂性和伪随机性，首先，对Liu混沌系统生成的混沌序列进行了改进，使改进后的序列具有理想的伪随机特性；然后，利用改进的Liu系统混沌序列对图像进行加密，提出了置乱与替代相结合的加密算法。实验表明该算法具有较强的抵御穷举攻击、统计攻击、已知明文攻击能力，因此，算法具有较高的安全性。