In view of problems such as abrasion,corrosion and blockage of tubular air preheater,and taking Hepo 350 MW supercritical circulating fluidized bed boiler unit as an example,the pipe wall temperature of air preheater is determined according to the prediction results of acid dew point through the intelligent temperature control strategy of air preheater inlet air temperature,so as to adjust the output of air heater,ensure that the inlet air temperature of air preheater is always above the acid dew point,so as to reduce the low-temperature corrosion at the end of air preheater. Combined with low oxygen combustion technology,the oxygen content of the boiler under different loads is finally determined through operation tests:2.7%-3.0% under 350 MW load,3.0%-3.2% under 310 MW load,and 3.2%-3.5% under 230 MW load,which effectively reduces the corrosion of the low temperature section of the air preheater. The secondary air inlet is used to inject limestone into the furnace to quickly respond to the desulfurization technology in the furnace,so that limestone can be directly injected into the micro oxidation dilute phase area in the furnace,shortening the desulfurization response time,reducing the amount of limestone used as the desulfurization agent in the furnace,avoiding the sharp fluctuation of SO2 content in the flue gas,and effectively improving the desulfurization efficiency in the furnace. By comparing the efficiency of each denitration spray gun and the position of the denitration spray gun,determining the high and low order of the spray gun efficiency,optimizing the spray gun of the SNCR system,increasing the setting of denitration spray gun in the inclined section of the secondary air duct,the average denitration efficiency under full load is improved,the amount of ammonia escape can be reduced,the consumption of denitration reducing agent of the unit is effectively reduced,and the risk of ammonia escape hydrogen sulfate ammonia corrosion and blockage of the air preheater are greatly reduced. Through the above technical means,the air preheater has been operating for 6 years,working in good condition and stable operation,which can provide reference for the operation and maintenance of air preheaters of similar units.