Abstract: In order to solve the problems of huge amount of data and slow transmission speed after image encryption, a new image compression encryption algorithm combined discrete cosine transform (DCT) with deoxyribonucleic acid (DNA) operation was presented. At first, the original image was compressed by means of DCT and encoded according to DNA sequence. Finally, based on DNA operation, DNA addition operation was implemented to the original image by Chen chaotic system and an encrypted image was obtained. Simulation results show that the algorithm not only improves the speed of image transmission and reduces the storage space, but also has good encryption effect and high security.