The invention provides a method for promoting breakage of cuttings through plasma jet flow during metal cutting. The method can promote separation of the cuttings during metal cutting machining, and belongs to the field of machining. Designated region modification is performed on a metal material to be machined by adopting the plasma jet flow containing components and active particles at differentconcentrations. The plasma jet flow is sprayed to the surface of the metal material to be machined, and the active particles can better penetrate into the material to promote atom groups consisting of atom layers to slide simultaneously on a sliding surface relative to other materials; occurrence of the sliding can increase incomplete failure of a sliding area; and microscopic particles in the plasma jet flow continuously penetrate into the surface of the material to reduce the elastic recovery of the material and the breakage resistance of the material, so that the cuttings are easier to break, and finally an aim of promoting the breakage of the cuttings.