Abstract: The corrosion behavior of P110 and TP110SS steels in NaCl solution containing saturated H2S gas, CO2 gas and H2S+CO2 gas by hanging slice immersion test and electrochemical test. The results show that corrosion of the steels in NaCl solution containing saturated H2S gas was the best serious, the corrosion product was deciduous iron-sulfur complex, it only provided weaker protection for the metal substrate. The corrosion rate of the steels in NaCl solution containing saturated CO2 gas was lowest, the surface of the steels exhibited typical “platform” and “tinea” corrosion images and the corrosion product mainly was FeCO3. The corrosion rate of the steels in NaCl solution containing saturated H2S and CO2 was between the two former, H2S corrosion was mainly and the corrosion product was loosen, the surface of the steels showed significant local corrosion. The corrosion of the tested steel in three kinds of saturated solutions was typical anodic dissolution type.