Abstract: This invention relates to a hammer mill used for feed processing, food processing or chemical industries. The said hammer mill has a casing, a rotor arranged in the casing and is provided with several hammers, and a vibrating screen with an active power source located around the rotor. The vibrating parameters can be set for control. In the cross section of the rotor, the width of the screen in the horizontal direction is more than that in the vertical height and it is symmetrical at the left and the right.