Abstract: In order to conduct heat transfer in heat pipe more effectively, it is more and more necessary to study the phase transition of capillary cores. By simulating the modal evaporation process in pores of a single capillary core, the film evaporation model of a single capillary core was proposed. Based on the phase field method, the model of evaporation from a single capillary bent surface was established by taking into account the Marangoni effect at the interface, the thermal buoyancy effect, the evaporative phase transition process at the interface and the reaction force generated by steam diffusion. Then the simulation results were compared with the experiment to verify the accuracy of the model. By analyzing the evaporation sensitivity at the interface, it is shown that there is a strong heat flux region near the three-phase contact line, which produces a large temperature gradient along the liquid bending level. This results in the surface tension gradient which, together with the buoyancy effect, causes a buoyancyhot capillary convection in the liquid film. The contact angle and superheat have significant influence on the evaporation rate.