The invention provides a quick clamping device for an electric hammer. The device is arranged on the striking head part of the electric hammer, comprises at least two clamping pieces which are used for clamping fastening pieces such as a nail and the like and is provided with magnetic devices, wherein a striking shaft which does reciprocating motion is arranged in the striking head part and acts on the fastening pieces such as the nail and the like; the magnetic devices can be magnetic parts arranged on the clamping pieces and also can be magnetic elements; and the clamping pieces are provided with clamping positions for clamping the nail through the mutual attraction of the magnetic parts, and are provided with loosening positions for releasing the nail through the mutual repulsion of the magnetic parts. In the device, the magnetic parts or elements are arranged on the clamping pieces, and the relative position between the magnetic parts or elements is varied, so that the fastening pieces such as the nail and the like can be clamped and released, and the device has a compact structure and a good clamping effect; and the characteristics of magnetic poles are fully utilized, so that the device has a novel design and high automation of degree.