A numerical simulation for heat exchanger with continuous helical baffles was carried out by using commercial codes of ANSYS CFX 12.0.The study focuses on the effects of helix angle on flow and heat transfer characteristics，and heat exchanger performance is evaluated by entropy generation number based on the analysis of the second law of thermodynamics.The results show that both the shell-side heat transfer coefficient and pressure drop decrease with the increase of the helix angle at certain mass flow rate.The latter decreases more quickly than the former.The tangential velocity distribution on shell-side cross section is more uniform with continuous helical baffles than with segmental baffles.The axial velocity at certain radial position decreases as the helix angle increases in the inner region near the central dummy tube，whereas it increases as the helix angle increases in the outer region near the shell.The heat exchange quantity distribution in tubes at different radial positions is more uniform at larger helix angle.The proportion of the entropy generation contributed by heat transfer in total entropy generation increases and the entropy generation number decreases with the increase of the helix angle at certain mass flow rate.