As the heat exchange device of the primary and secondary circuits in the lead-bismuth fast reactor (LFR), the steam generator needs to consider its heat exchange performance and safety. To achieve a better heat transfer effect and reduce the possibility of pipeline rupture caused by heat transfer deterioration, research on the optimal design of heat transfer pipelines has very important academic significance and engineering application value. Since the hydrophobic surface can promote the nucleation of bubbles while the hydrophilic surface can increase the critical heat flux, the purpose of enhancing heat transfer can be achieved by designing a hydrophilic-hydrophobic mixed surface of the heat transfer pipe. Based on the improved Lattice Boltzmann method (LBM) phase change heat transfer model, this paper mainly studies the bubble dynamic behavior of the working fluid in the U-shaped tube and the heat transfer performance of the tube wall surface and reveals the mechanism of the mixed wetted wall to enhance heat transfer. The results show that the spacing, number, and width of the hydrophobic points are three important factors that affect the enhanced boiling heat transfer on the wall, which determine the bubble shape and heat flux distribution characteristics of the wall boiling. Choosing the proper hydrophobic point parameters can get an ideal heat transfer surface, and the relevant results provide some suggestions for the wall design of the heat transfer tube.