In this study, improvements upon the airside performance of wavy fin-and-tube heat exchangers are made by punching holes on top of leeward wavy fin surfaces. Detailed parametric studies concerning location, width and length of holes are performed by 3D numerical simulations. It is found that punching holes on top of wavy fin surfaces can result in 7% decrease in thermal resistance while punching holes on top of leeward parts and bottom of windward parts of wavy fins will only increase pumping power without any heat transfer enhancement. Increasing width of holes imposes negligible effect on heat transfer characteristics. Conversely, increasing length of holes is comparatively effective. Punching holes with width of 1 mm and length of 12 mm can result in a decrease in thermal resistance up to 10%.