Abstract: Two layered predictive control have high on line complexity and long on line solving time on large scale systems. Through theoretical analysis of computational complexity and implementation of simulation for the steady state target calculation(SSTC) layer and the dynamic matrix control(DMC) layer, it is concluded that control inputs’ numbers and control horizon are the main factors that affect algorithm’s computational efficiency, and the desired algorithm’s time complexity is proportional to the cube of product of control inputs’ numbers and control horizon. And it is valuable to controller’ design in industry process.