Abstract: Aiming at the problem of insufficient encryption of a single chaotic system, the main proposed algorithm is an image encryption algorithm based on improved LCL composite chaotic system and DFT variation. Firstly, DFT transformation of images is carried out, chaotic sequences generated by high-dimensional Lorenz system are randomly combined and arranged, and a group of obtained index sequences are combined with an improved Cat system to scramble plaintext images; Secondly, the pseudo-random sequence of Logistic map is designed by using hyper-Lorenz chaotic system, and the encrypted image is obtained by XOR processing. In order to achieve better encryption effect, repeat the above steps for cyclic encryption. The simulation results show that the algorithm designed in this paper has excellent encryption effect, large key space, strong sensitivity to plaintext, and can effectively resist statistical attacks.