The chemical reaction process of corrosion from flue gas of Municipal Solid Waste (MSW) incineration to metal heating surface in MSW incinerator is analyzed. The impacts of high temperature corrosion rate from chloride to immersed tube, superheater are discussed. The reason of metal tube corrosion in MSW incinerator is related with flue gas composition, flue gas temperature, metal tube temperature and anti-corrosion properties of metal tube.