The invention discloses a manufacturing method of a metal interconnection structure. The method is different from conventional double-patterning scheme. In the method brought forward by the invention, first of all, a group of grooves are formed in a dielectric sacrificial layer by use of a conventional single Damascus technology, metal is filled in the grooves so as to form a first set of metal patterns of the metal interconnection structure, then the dielectric sacrificial layer is removed, cover layers whose thicknesses can be accurately controlled are formed around and among the first set of the metal patterns by taking the metal of the first set of the metal patterns as a core, side walls are formed through etching back the cover layers, a second set of metal patterns by filling a gap among the side walls, during the back-etching process, the gap depth among the side walls is deepened, and the deepening processing can enable the depth of the second set of metal patterns formed by subsequent filling and the previously formed first set of metal patterns to be consistent, such that the double-patterning process of the metal interconnection structure is finished. Since the second set of metal patterns is inserted into the first set of metal patterns, the purpose of multiplying pattern density is realized. The manufacturing method is simple in process, and the shape of the metal patterns is easily controlled.