Abstract: The types of coal burned by supercritical DC boiler of a power generation company are complex and varied and deviate from the designed type of coal. Due to the decrease of ammonia spraying uniformity in denitration system, the poor linearity of ammonia spraying regulating valve and the low denitration efficiency in low load section, ammonia escape increases, resulting in increased resistance of air preheater, and the relative output of fan decreases relative to boiler capacity. In order to meet the requirements of power grid active load in peak load section, Forced to reduce boiler oxygen operation. Long time hypoxia or local anoxia operation makes high temperature corrosion of water wall pipe serious. In order to effectively slow down the high temperature corrosion rate of the water wall, the company based on CO online measurement control, to achieve accurate grasp of the combustion conditions in the furnace and the distribution of the power field in the furnace, so as to realize the fine control of the boiler's primary and secondary air, while ensuring the boiler NOx emission standards, slow down the corrosion rate of the water wall in the peak load section.