The present invention relates to the field of magnesium and magnesium alloy processing, and discloses a use of aluminum-zirconium-carbon (Al—Zr—C) intermediate alloy in wrought processing of magnesium and magnesium alloys, wherein the aluminum-zirconium-carbon intermediate alloy has a chemical composition of: 0.01% to 10% Zr, 0.01% to 0.3% C, and Al in balance, based on weight percentage; the wrought processing is plastic molding; and the use is to refine the grains of magnesium or magnesium alloys. The present invention further discloses the method for using the aluminum-zirconium-carbon (Al—Zr—C) intermediate alloy in casting and rolling magnesium and magnesium alloys. The present invention provides an aluminum-zirconium-carbon (Al—Zr—C) intermediate alloy and the use thereof in the plastic wrought processing of magnesium or magnesium alloys as a grain refiner. The aluminum-zirconium-carbon intermediate alloy has the advantages of great ability in nucleation and good grain refining effect, and achieves the continuous and large-scale production of wrought magnesium and magnesium alloy materials.