Pneumatic impact hammer

The utility model relates to a pneumatic impact hammer which comprises an outer cylinder, wherein, blades are arranged on the outer wall of the outer cylinder. The blades are spiral blades or straightblades. The pneumatic impact hammer is provided with the blades on the outer wall of the outer cylinder, when in use, the pneumatic impact hammer is connected with a long spiral drill rod, the rotation directions of the long spiral drill rod and a protective cylinder are reverse during the construction process, a down hole head impacts a rock up and down under the action of high-pressure air, theresidual gas flies dust and stone ballast of the rock in a hole after the down hole head breaks the rock, and the broken stone or earth is transferred onto the spiral blades on the long spiral drillrod through the rotation guide of the blades, thereby discharging the broken stones and the earth out of a pile hole and improving the hole-forming efficiency and the hole-forming quality.