Abstract: In view of status of low desulphurization efficiency and no automatic control of desulfurization process in original flue gas desulfurization system of Thermal Power Plant of Daizhuang Coal Mine, the paper analyzed technical process of ammonia flue gas desulfurization, designed integrated automation monitoring and control system of ammonia flue gas desulfurization based on PLC. The system realizes monitoring and control of entire flue gas desulfurization process, and can complete automatic control of desulfurization process according to monitored data in field, which improves automation level of the thermal power plant.