From the two aspects of theory and experiments, the different cut-off grades for ore drawing and the relations among them were studied and some important conclusions were drawn, that are, although the different Cut-off Grades for Ore Drawing were put forward originally based on different theory, but there are still inherent substantial relations among them; both extreme cut-off grade ore drawing and undiluted ore drawing are special ways of combined cut-off grade ore drawing, but have different characteristics, application conditions and can cause different economical effects; in practice suitable combined cut-off grades shall be adopted for ore drawing.