The handle of the coffee bean grinder is connected with the cover, and the cover is immediately fastened on the cylinder, and a polygonal groove is set tightly on the cover. One end of the grinding shaft can be matched with the polygonal groove, and the cover is set on the end of the grinding shaft that can be matched with the polygonal groove, so that the user can grasp the coffee grinder cylinder with one hand. Manipulate the handle of the coffee grinder with the other hand to push the cylinder cover and the grinding shaft to rotate the grinding.