Abstract: To investigate the effect of different oxygen content on corrosion resistance of steels, carbon steel and weathering steel with different oxygen content of (20~200)×10-6 were smelted. By means of SEM inclusion analysis, polarization curve test, full immersion test, the change rules of inclusion type, shape, quantity, size and corrosion resistance under different corrosion environments with the change of oxygen content in steel were studied. The results show that with the increase of oxygen content in the steel, the inclusions in the steel change from long strip MnS, Al2O3 to granular silicate inclusions, and the number and size of inclusions increase gradually, for example, with the oxygen content from 20×10-6, 60×10-6 to 195×10-6, the number fraction of MnS decreases from 69.9%, 23.7% to 5.8%, the number fraction of silicate increases from 3.4%, 54.9% to 73.2%, the total area fraction of inclusions increases from 0.01%, 0.04% to 0.25%, and the equivalent circle diameter (ECD) increases from 0.78 μm, 1.15 μm to 4.65 μm; The pitting potential showed a positive trend, with an overall increase of about 40 mV; The full immersion corrosion rate first decreases and then increases, following the cubic function change rule. When the oxygen content increases from (20~30)×10-6 to 60×10-6, the corrosion rate of carbon steel decreases by 53%, and the corrosion rate of weathering steel decreases by 18%. The corrosion resistances of carbon steel and weathering steel are improved, and the corrosion rate of weathering steel is obviously lower than that of carbon steel, which is below 3 mm/a. With the corrosion time extending from 24 h, 48 h to 96 h, the corrosion rate of carbon steel and weathering steel decreased significantly, and the corrosion gradually slowed down. According to the analysis, there are mainly long strip sulfides in the steel with the oxygen content of (20~30)×10-6 . When the steel plate undergoes pitting corrosion, the sulfides exposed on the pit wall will rapidly dissolve, accelerating the corrosion of the steel. The long strip sulfides is reduced in the steel with the oxygen content of (60~85)×10-6, and most of them are replaced by silicate composite inclusions that are not easy to induce pitting corrosion, and the corrosion propagation is restrained, which is shown by good corrosion resistance. When the oxygen content is increased to 195×10-6, the average equivalent circle diameter of inclusions in the steel reaches to four times of that of the steel with the oxygen content of 60×10-6 , and the total area fraction of inclusions reaches to six times of that of the steel with the oxygen content of 60×10-6. Such a large number of inclusions as the source of pitting corrosion cause the matrix to be vulnerable to serious corrosion, which is characterized by poor corrosion resistance. Therefore, when the oxygen content is in the range of (20~100)×10-6, the corrosion resistance of steel in the full immersion corrosion environment is enhanced due to the combined effect of the reduction of long strip sulfide that is easy to induce corrosion and the increase of solid solution oxygen to raise the matrix potential; When the oxygen content is in the range of (100~200)×10-6, the corrosion resistance of the steel is weakened due to the sharp increase of inclusions. Economical corrosion resistant steel can be developed by increasing oxygen content appropriately.