针对彩色图像加密的特点，为了减弱图像相关性、加大密钥空间、提高安全性，提出DNA序列和分数阶Chen超混沌系统彩色图像加密算法。该算法将三维的彩色图像转换成三个二维DNA序列矩阵，利用分数阶Chen超混沌系统产生的混沌序列将三个DNA序列矩阵进行位置置乱，将置乱的三个DNA序列矩阵分别分成相等的小块，利用分数阶Chen混沌系统和DNA序列加法法则将块相加，重新组合小块并利用DNA解码规则得到彩色加密图像。仿真结果和安全性分析表明，与其他图像加密算法对比，该算法降低了算法空间和时间需求，相关性低，密钥空间大，密钥敏感性高，安全性更高，具有更强的抵御各种攻击能力。

According to the characteristics of color image encryption, in order to reduce the correlation of images, increase the key space and improve the security, the color image encryption algorithm based on DNA sequence operation and fractional order Chen hyper-chaotic system is proposed. The three-dimensional color image is transformed into three two-dimensional DNA sequence matrices. The chaotic sequences which is generated by fractional order Chen chaotic system are used to scramble the locations of elements from three DNA sequence matrices, and then divide three DNA sequence matrices into some equal blocks respectively. The proposed algorithm adds these blocks by using fractional order Chen chaotic system and DNA sequence addition operation. The encrypted color image by decoding the DNA sequence matrices and recombining the blocks. The simulation results and security analysis show that the proposed algorithm has the advantages of low space, short time, low correlation, big space of the key, high sensitivity of the key, high security and strong resist attacks ability compared with other image encryption algorithms.