A cryptosystem based on multiple chaotic maps is proposed. It is composed of a function f(?), a 2D chaotic map and two cascaded chaotic subsystems. The iteration times of the cascaded subsystem constructed by simple chaotic maps are changed with the outputs of the 2D chaotic map. Plaintext and the outputs of the cascaded subsystems are handled by the function f(?) to generate ciphertext. Simulation tests and security analyses indicate that the proposed cryptosystem is featured by large key space, high sensitivity to key, and resistance to statistical attacks and differential attacks.