A two-dimensional transient temperature model was established to predict the temperature distribution between the wellbore and the surrounding strata. The model was discretized by finite volume method and solved by under-relaxation iterative method. The effectiveness of this model is verified by comparing it with the previous wellbore temperature model. The distribution rule of wellbore temperature when the leakage occurs in the open hole section of geothermal well was obtained, and the sensitive factors affecting the wellbore temperature distribution were analyzed. The results show that the temperature distribution curve of the annular drilling fluid changes dramatically at the location where the leakage occurs. The continuous loss in the wellbore will reduce the circulation temperature of drilling fluid in the annulus and drill pipe, which reflects the cooling effect of the loss on drilling fluid, especially in the part of the bottom hole near the loss zone. After the same drilling fluid circulation time, the well head temperature and bottom hole temperature in the case of loss are significantly lower than those in the case of normal circulation. The occurrence of open hole formation loss not only has an important impact on the wellbore temperature distribution above the loss point, but also has a significant impact on the wellbore temperature distribution below the loss point.