To address water-wall corrosion in utility boilers particularly super-critical boilers with low NOₓ combustion, the achievements and experiences of USA studies in corrosion mechanisms and mitigation technologies are systematically reviewed. The main corrosion mechanism is: the deposition of FeS on water-walls under reducing atmosphere and the subsequent FeS decomposition and oxididation on the walls under alternating reducing/oxidizing atmosphere cause severe corrosion. While refined combustion optimization can promote in-flame FeS oxidation to alleviate corrosion, enhancing corrosion resistance of the material through thermal spray and weld overlay is effective measure.