The atmospheric-corrosion of the pressurized-vessel steel(ASTM-A516)was studied over the temperature range of 200-400℃ in a simulated water vapor containing NaCl environment. The effect of NaCl surface coating (2mg/cm^2) on the corrosion kinetics was also evaluated, as compared with those without coating. The results showed that the corrosion kinetics of A516 steel obeyed the parabolic rate law, regardless of temperature and coating. In general, the corrosion rate increased with temperature, and the rates of the steel with NaCl coating are higher than those without coating at all temperature. The corroded scales formed on the steels(with or without NaCl coating)consisted of mostly Fe2O3,Fe3O4,andminor Fe OOH and FeCl3-nH2O.The chlorine ion was always detected to be located at the interface between the substrate and the interior scales on the steel with NaCl coating, leading to further corrode the substrate, as a consequence of the faster corrosion rate.