Abstract: The pitting corrosion behavior of 445J2 ultra-pure ferritic stainless steel and 316L austenitic stainless steel at different temperatures and different concentrations of Cl-was studied by electrochemical test methods. The critical pitting temperature of the two stainless steels was studied by constant potential polarization test method. The scanning electron microscope（SEM） was used to analyze the pitting morphology. The results show that the critical pitting temperature of 445J2 stainless steel is 48℃, which is higher than 20℃ of 316L. The pitting corrosion resistance of the former is better than that of 316L stainless steel. The pitting corrosion behavior of the two kinds of steels are obviously intensified with the increase of ambient temperature.