Abstract: In the light of the energy balance equation of vertical conduit flow and combined with the computational method for the Ramy wellbore temperature distribution, the paper gives the distributions of wellbore pressure and temperature when CO₂ is injected at different injection rates, injection temperatures and injection time etc. and verifies it by actual data of injection test at Cao-8 Well in Subei Oilfield. The result is that the error percentage of pressure is 3.8%and the error percentage of temperature is 2.5%. On the basis of this, the paper further discusses the factors influencing wellbore temperature of CO₂ injection well and believes that the injection rate of CO₂ is the main influence factor.