"X" STITCHING METHOD FOR MOUNTING UPPERS BY MEANS OF THE STRING-LASTING SYSTEM, the method comprising using a string traction for closing the edges of an upper, against a mold, for assembling a shoe, the method wherein a "X" stitching is applied to the upper, using a sewing machine or manual sewing, to generate a cross vector tractioning, resulting in full, proportional, symmetric and simultaneous fitting of the upper to a body and sole of the mold, in the region of the insole, to completely cover the three different areas of assembly of shoes, including the toe, the area in the region of the shank and the rear; wherein the sewing order of the "X" stitching can be reversed, or mirrored, or even initiated or terminated at other points of the circuit, depending on the sewing equipment available, or the operator's preference, and in that the method further comprises performing the following steps, in a right-to-left or left-to-right stitching direction: - a first procedure of determining the points of reference for the start and the end of the stitching, wherein the position of the start of the stitching and of the "X" are determined at the time of the stitching, only in the execution of the shoe models, because on the production line, said positions have already been previously marked, usually by small cuts, and wherein the ends of the traction string must have sufficient length to facilitate their fixing to a traction element; - a second procedure of demarcating the position of the X stitching in the upper, at this moment the right point is determined through which the traction string must pass, from one side to another and vice versa; wherein said position of the "X" is visible in the references,,,,, is marked in the execution of the shoe models, while in the production line it comes previously marked, and determines the inversion of the stitching side of the upper, in the region of the shank; and from this point, the upper is tractioned, in a vector direction, resulting in the full fitting of the upper, against a surface of the mold; a traction angle being variable, depending on the model of shoe to be assembled; - a third procedure is the sequence of the stitching overlapping the traction string, after the demarcating step, wherein the stitching begins at reference, observing the progressive sequence until where the operation ends; - a fourth procedure of assembling the upper and the traction string on the mold, after the upper is grouped with the mold, the ends of the traction string are tractioned in accordance with a vector direction indicated throughout the references and, resulting in the full closure of the edge of the upper on the mold, with or without insoles, in accordance with the vector direction, wherein the "X" stitching enables assembly of all models of shoes and all known heights of heels, and after said assembly the sole can be glued or directly injected to the upper. - a first procedure of determining the points of reference for the start and the end of the stitching, wherein the position of the start of the stitching and of the "X" are determined at the time of the stitching, only in the execution of the shoe models, because on the production line, said positions have already been previously marked, usually by small cuts, and wherein the ends of the traction string must have sufficient length to facilitate their fixing to a traction element; - a second procedure of demarcating the position of the X stitching in the upper, at this moment the right point is determined through which the traction string must pass, from one side to another and vice versa; wherein said position of the "X" is visible in the references,,,,, is marked in the execution of the shoe models, while in the production line it comes previously marked, and determines the inversion of the stitching side of the upper, in the region of the shank; and from this point, the upper is tractioned, in a vector direction, resulting in the full fitting of the upper, against a surface of the mold; a traction angle being variable, depending on the model of shoe to be assembled; - a third procedure is the sequence of the stitching overlapping the traction string, after the demarcating step, wherein the stitching begins at reference, observing the progressive sequence until where the operation ends; - a fourth procedure of assembling the upper and the traction string on the mold, after the upper is grouped with the mold, the ends of the traction string are tractioned in accordance with a vector direction indicated throughout the references and, resulting in the full closure of the edge of the upper on the mold, with or without insoles, in accordance with the vector direction, - a third procedure is the sequence of the stitching overlapping the traction string, after the demarcating step, wherein the stitching begins at reference, observing the progressive sequence until where the operation ends; - a fourth procedure of assembling the upper and the traction string on the mold, after the upper is grouped with the mold, the ends of the traction string are tractioned in accordance with a vector direction indicated throughout the references and, resulting in the full closure of the edge of the upper on the mold, with or without insoles, in accordance with the vector direction, wherein the "X" stitching enables assembly of all models of shoes and all known heights of heels, and after said assembly the sole can be glued or directly injected to the upper.