As China’s offshore drilling and production projects gradually march into the deep water, the requirements for scientific and technological progress are imminent. The occurrence of the 2010 Macondo disaster has presented a serious challenge to the safety of deepwater in technology. The deepwater wellbore consists of several layers/channel barriers, which constitute the wellbore barrier system and have a complicated structure. With the increase of water depth and well depth, the temperature of oil and gas produced at the wellhead is getting higher and higher, and the fluid in the annulus of the casing is heated by the conduction and convection of fluids such as oil and gas produced in the high temperature formation. Up to 60 degrees Celsius, the thermal expansion of the annulus fluid can cause the casing to burst, which can cause significant loss of personnel and property. Therefore, accurate temperature calculation of deep water wellbore is the key to the calculation of trap pressure prediction. The calculation of the wellbore temperature is affected by the oil casing and the thermophysical parameters such as the size of the wellbore, fluid composition, flow regime, casing and cementing sheave. By appropriately simplifying the model and sensitivity analysis, it is found out the dominant factors which affect the temperature profile.