Wavy channels are being used in compact heat exchangers. Adding in -Flow barrier with low increase in pressure drop can increase the Nusselt number in these channels. In some barrier location for low Reynolds number with no vortex, barrier will create vortex and for higher Reynolds number with vortices, a barrier in some positions can change the vortex size or even eliminate the vortices. Then barrier in some situations can increase or decrease the pressure drop or Nusselt number depend on the barrier situation. The governing equations including continuity, momentum and energy are solved by the control volume method. The simulation has been done using the SIMPLE algorithm and using the Fortran programming. The results have been obtained in laminar flow for three different Reynolds numbers (100, 150, 200) and two different Prandtl numbers (3, 6) at 132 different locations of a barrier. In a case, about 42% reduction in maximum pressure drop, and, in another case about 52% increase in the Nusselt number in compare with no barrier channel has been reported. Finally, the best situation (with maximum Nusselt number and performance coefficient) has been found and reported.