The high-temperature heat pipe with liquid metal as the work material has a very high heat transfer capacity, which utilizes the phase change of the work material to transport a large amount of heat from the evaporation section to the condensation section with a very small temperature drop, which greatly facilitates the high-temperature heat transfer of nuclear reactors. In this paper, the VOF two-phase flow model is used to simulate the high temperature heat pipe by CFD. First, the physical model of the high temperature heat pipe is established according to the heat pipe heat transfer principle and existing experimental data. Based on the heat pipe model, Ansys software is used to conduct modeling, grid drawing and simulation research. A user-defined function (UDF) is needed to import the thermal properties of sodium and conservation equations for the simulation. The process of bubble nucleation, growth, aggregation and separation from the wall of the liquid pool in the evaporation section of the heat pipe was simulated. It was found that with the increase of heating power, the boiling phenomenon in the liquid pool became more intense, and the temperature and pressure in the evaporation section also increased significantly. By setting different heat transfer boundary conditions in the condensing section, the temperature equalization and heat transfer efficiency of the heat pipe under the forced convection heat transfer condition are significantly improved. By changing the heating power and heat dissipation mode, the changes in the flow field and temperature field in the heat pipe are investigated.