The invention discloses a preparation method of a gradient functional material based on friction-stir welding. The preparation method comprises the following steps: adding a reinforced phase materialto a substrate by means of a right-angled triangular prism groove structural design on the substrate; and generating heat by mutual friction of a stirring head and a material in a substrate welding region, wherein the substrate welding region is softened plastically and the material in the substrate welding region drives the reinforced phase material to flow plastically under the action of the stirring head, so as to form a uniform gradient functional material from the material in the substrate welding region and the reinforced phase material. The method disclosed by the invention does not need special environments such as vacuum, temperature, electric field and magnetic field, and is low in preparation cost; by means of a solid state processing mode, formation of cracks, pores and oxidesin the material can be avoided effectively, and the gradient functional material which is high in compactness and uniform to mix can be obtained. Various types of gradient functional materials can beprocessed; the preparation method is a green processing technology, and the gradient functional material which is higher in mechanical property can be obtained.