The invention discloses a dew-point-corrosion-resistant coating material, a preparation method thereof and a construction process thereof. The coating material comprises, by mass, 20-60% of binder, 1-10% of nano material dispersion slurry, 1-10% of graphene dispersion slurry, 5-15% of sheet shielding material, 5-30% of corrosion-resistant pigment, 5-20% of extender pigment, 0.5-5% of auxiliary and0-40% of dispersion medium. The coating method is prepared by adopting a special preparation method and is better in homogenization and stable in storage. The coating material has excellent dew-point-corrosion-resistant performance and good in long-time heat-resistant performance, is compact and high in hardness, has good resistance to erosion of flue gas and the like and has good bonding adhesiveness to metal base materials.