The invention provides a rapid manufacturing method for a metal 3D printing injection mold of a structure facing a gradient space. The rapid manufacturing method comprises the steps that the injection mold is designed according to the characteristics of an injection molded part at first, meanwhile, the injection mold is partitioned according to the service characteristics and the molding characteristics of the injection mold in the injection molding process, decoupling optimization is conducted, and the injection mold is divided into a molding area, a supporting area and a function area; then the molding area of the injection mold is manufactured through a metal 3D printing mode; the supporting area of the injection mold is manufactured through a machining mode; the function area of the injection mold is manufactured through a metal 3D printing mode and is a molding insert or a cooling insert with a conformal cooling water channel; and the molding area, the supporting area and the function area are fastened and connected in a bolted connection or inserted connection mode finally. According to the rapid manufacturing method for the metal 3D printing injection mold of the structure facing the gradient space, the manufacturing efficiency of the injection mold is improved, the service life of the injection mold is prolonged, meanwhile, the cooling rate of the injection mold is increased so that the injection molding efficiency can be significantly improved, and the problem that the inconsistency is required by the material performance in the service process is solved.