To address the aggravated low-temperature corrosion of tail-end equipment in coal-fired boilers and ensure safe， economical and environmentally friendly operation of generating units， this study took a 300 MW boiler in a power plant as the research object. Field maintenance and operation data analysis were carried out to diagnose tail-end equipment such as air preheaters and flue gas coolers. The results show that the formation and condensation of ammonium bisulfate and ammonium chloride are the core mechanisms causing corrosion and blockage. Root causes include increased chlorine content from sludge co-firing， excessive ammonia escape in the selective catalytic reduction （SCR） denitrification process， and low flue gas temperatures due to deep peak regulation. An integrated control strategy was implemented， involving optimization of sludge co-firing ratio to 8%， catalyst replacement and ammonia injection optimization， material upgrades， adjustment of flue gas cooler parameters， and installation of a dynamic flue gas temperature control system. Practical results demonstrate that these measures effectively mitigate corrosion and blockage， providing valuable engineering experience for similar units.