In order to simulate phase distribution for carbon dioxide injection wellbore, provide theoretical basis for carbon dioxide flooding, save cost on well logging, improve oil recovery efficiency, the phase distribution model was established for carbon dioxide injection wellbore. This paper established the temperature and pressure coupled model along the wellbore, based on the theory of heat transfer, fluid mechanics and energy conservation law. Then the phase distribution map for carbon dioxide injection wellbore can be drawn combined with carbon dioxide phase diagram. At last, the graphical user interface has been composed based on the MATLAB program for the convenience of the user. The phase distribution model which was established by this paper for carbon dioxide injection wellbore was applied to a test well. Through the comparison of data of temperature and pressure between monitoring and simulating, the relative average errors between measuring points and calculating points were obtained. The relative average temperature error was 0.75% and the relative average pressure error was 3.2%.It can mainly satisfy the requirements of accuracy for establishment of phase distribution model for carbon dioxide injection wellbore. The model can conduct production of carbon dioxide flooding, optimize the injection parameters and increase oil recovery efficiency.