Abstract: Off-line optimization and feasibility analysis of model predictive control used in the synthesized process of potassium salt unit are presented. Meanwhile, optimal temperature distribution of the first hydrolysis tower reactor under normal condition are got. The dynamic mechanism model of the first hydrolysis tower reactor was obtained based on production technology. The feasibility use of the model predictive control in the system is analyzed by using Matlab simulation. The result shows that this method could enhance the stability of the process and promote product content. Finally, it was proved that the computerized optimal control could be better used in this process.