Abstract: For overcoming the contradiction between the performance improvement and fluid flow resistance increase in shell-and-tube heat exchanger,a new concept of "Sideling Flow" in shell side is presented,and a type of new high efficiency energy saving shell-and-tube heat exchanger with leading type shutter baffles in shell side,sideling flow heat exchanger is invented.Besides,the"Field Synergy Principle" is adopted to analyze its heat transfer enhancement mechanism,and it is indicated that there is the perfect synergy between the velocity field and temperature grads field in shell side of this type of new heat exchanger.Effects of the structure parameters on the fluid flow and heat transfer are investigated through numerical simulation,and the numerical results are in good agreement with the experimental data.