In coal-fired boilers of large thermal power plants, the temperature field inside the furnace reflects the important impact on the ignition and combustion of coal powder and the safety of the boiler. Unstable combustion reduces boiler efficiency, increases noise and pollutant emissions. Meanwhile, in recent years, the technology of furnace flame temperature monitoring instruments has become increasingly mature, and temperature field optimization DCS closed-loop control is particularly important. LN2000 DCS has been well applied in temperature field optimization of power plants such as Laiwu, Jiaxiang, and Weihai. Taking a certain power plant as an example, the DCS closed-loop control of temperature field will be introduced in detail below.