The invention relates to a method for producing sodium caseinate by an extrusion process, belonging to the technical field of sodium caseinate. A sodium caseinate sample produced by the extrusion process has a good protein characteristic, all physicochemical indexes of the sodium caseinate sample can accord with the national standard, most importantly, the sodium caseinate sample is high in viscosity and good in color and luster and has a normal flavor, the method has the main advantages of short consumed time and high conversion efficiency in a conversion process, raw materials are almost free of a browning reaction and has a low albuminous degeneration degree because procedures such as re-dissolution of casein, acid precipitation, and colloid grinding in a conventional process are omitted, and the higher product quality standard can be met.