The concepts of cross composition cellular automata and random composition cellular automata are introduced, and their feasibility in application to cryptosystem is analyzed. We use the inverse iteration of cellular automata to encrypt, and construct two encryption systems based on composition cellular automata. The new encryption systems effectively solve the problem of one way error diffusion in a single cellular automata system and acquire large key space with small rule radius. Simulation experiment shows that the diffusion and confusion properties of the new composition system are ideal, it resists brute attack and differential cryptanalysis.