The wet CO2 corrosion is a complex process especially when crude oil is contained in the corrosion system. In this paper the corrosion behaviors of 3Cr alloy steel L245 and 16Mn steel in oil-water mixture emulsion with 10% 30% 80% water cut under various temperature in a dynamic condition were investigated respectively. The corrosion product scale was characterized by SEM EDS and XRD. The results show that 3Cr steel exhibited the best corrosion resistance. At 10% and 30% water cut the corrosion scales of the three steels were thin and compact and dominated by (FeCa)CO3. At 80% water cut a Cr-rich layer formed on surface of 3Cr steel and the scale of L245 was compact internal but porous external while the scale of 16Mn was compact but cracked and spalled. The corrosion rate of 3Cr steel decreased with increasing temperature at 80% water cut but the corrosion rate of 16Mn increased sharply with increasing temperature due to the corrosion scale spalled. The corrosion rate of L245 exhibited a maximum value at 60?. Combined the morphologies of scales and the corrosion rate it can be found that the corrosion rates of these steels increased obviously when the solution changed from water-in-oil to oil-in-water but the Cr element caused a reduction of corrosion rate at high temperature and high water cut by forming Cr-rich layer. However pitting corrosion formed under the thin and cracked Cr-rich layer.