The drum selection machine is a selection device for separating impurities which are shorter or longer than the particles in the grain, and is used for removing the hazelnuts, grass seeds and oats contained in the wheat during the flour processing. Type A can simultaneously remove impurities such as hazelnuts and oats (including the secondary flow treatment drum), and the H type can remove impurities such as hazelnuts and oats (including the secondary flow treatment drum). This product is used in wheat flour cleaning and lower foot treatment in flour mills. The design principle is also used in the following areas: rice plant grading and broken rice processing; seed station (field) selection; beer factory, oatmeal factory separation materials.