The invention discloses a zinc alloy large-plane die casting dressing technology. The technology comprises the following steps: utilizing a jig consisting of an upper clamping plate and a lower clamping plate to lock and shape a die casting, thus the die casting is in an elastic deformation state and the flatness of the die casting is up to 10-15 microns; placing the jig in an oven, and heating so that the die casting is subjected to elastic deformation, the stress is relieved, the demand on the flatness can be met; opening the door of the oven, taking out the die casting, and cooling the diecasting naturally to the room temperature; and loosening the jig, and taking out the die casting for the next working procedure. The technology provided by the invention is simple in operation, and has the advantages of good stability, high production efficiency, great market value and huge market potential, no need of plentiful manpower and material resources and no damage to surface of the product; the stress of the product can be eliminated automatically, the product stability is good, the product can not deform again; and large-plane die castings can be effectively shaped, and the high demands of modern production on the product quality and the production efficiency can be met.