An impact hammer with pre-pressing damping and buffering effect includes a handle, outer barrel, air inlet, internal slide, actuating cylinder, air flow switching module and air inlet coupling portion. A front damper is assembled between the front end of the internal slide and the front end wall of the holding space and is characterized by a two-section pre-pressing rear damper assembled between the rear end of the internal slide and the rear end wall of the holding space. The two-section pre-pressing rear damper includes superposed upper and lower elastic buffers. At least the lower elastic buffer is pressed by a pre-pressing member to the preset degree. When the impact hammer yields recoil force under the impaction of the piston, the pre-pressing rear damper is employed to realize stronger buffering effect, so that the impact force is not much affected, thereby improving the impact efficiency and yielding excellent buffering effect.