The invention discloses a method for preparing large-size functionally graded materials through stirring and friction. A series of problems that in an existing preparation method, the cost is high, the energy utilization rate is low, contamination is large, the material size is small, and combination of an air hole and an interface is not tight are solved. By means of the heating, plasticizing, stirring and extruding effects in the stirring and friction machining process, two or more layers of different materials are partially mixed to be uniform into a layer of materials of different ingredients, on the basis, one or more layers of materials are stacked, stirring and friction are performed, and therefore another layer of materials of different ingredients is manufactured; due to repeatedmachining, the multiple layers of tightly-combined functionally graded materials of different ingredients are formed, and the method is easy to implement and control, environmentally friendly and capable of being industrially applied conveniently.