Abstract: To improve the thermal efficiency of intermediate heat exchanger (IHX) in high temperature gas-cooled reactor, the influence of artificial roughness on heat transfer enhancement was simulated by CFD software. From the aspects of flow distribution, axial velocity, transverse velocity, turbulence kinetic energy, temperature field and wall heat transfer coefficient, a preliminary research comparing the smooth tube and rough tube was made. The results show that artificial roughness can destroy the adhesive layer of turbulent boundary layer, enhance lateral disturbance, and greatly improve the efficiency of heat convection. The frictional resistance also increases because of the decrease of axial velocity. As a result, the research can provide necessary theoretical support to design a rough tube with the best heat transfer efficiency.