Abstract: In order to achieve the goal of "one-key start-stop" for desulfurization island in thermal power plants, an intelligent, reliable and efficient desulfurization control system is the key premise to achieve this goal. The optimization and transformation of the pulping system, the pulping supply system and the oxidizing air system were put forward in Huaneng Qinbei Power Plant, aiming to improve the system measuring points, improve the accuracy of monitoring parameters and optimize the system control strategy. An intelligent auxiliary operation system is established through historical data, and the combination of circulating pump and pH value control range are given. It can improve the automation and intelligence level of the desulfurization system and make the desulfurization system run efficiently and stably in closed loop.