Abstract: The effects of pH and dissolved oxygen (DO) content on the fretting corrosion behavior and damage mechanism of Inconel 690TT alloy in high-temperature and high-pressure water environment were studied. The results show that the coupling effect of pH and DO did not exhibit a specific pattern on the fretting corrosion behavior of the alloy. The change in pH did not alter its fretting corrosion damage mechanism, but affected the process of damage. When the mass concentration of dissolved oxygen (DO) was 100 μg/L, the degree of wear was the lightest. Appropriate DO content was beneficial for the formation of the third body layer (TBL) to reduce wear, but excessive DO content could increase corrosion and aggravate wear degree.