The invention relates to a making method of a flame-retardant high-temperature-resistant electromagnetic-radiation-resistant composite functional fabric. The method is characterized by comprising the following steps: (1) treating aramid short fibers through a picking machine, a cotton blending machine and a cotton slitting machine, and opening and purifying through a cotton cleaning machine; separating the aramid short fibers into single fibers by cotton carding of bundled or blocked fibers to obtain uniform cotton carding bars; (2) combining and mixing the metal fibers and the aramid short fibers, and drawing to obtain bars; (3) performing a roving process of the bars on a roving machine, wherein the traction ratio during roving is 5-12 times, and the roving twisting coefficient is 100-122; (4) drawing and twisting rough yarns in a spinning frame to obtain blended yarns of the aramid short fibers and stainless steel fibers, wherein the traction ratio of the spinning frame is 15-40 times, and the twisting coefficient is 280-350; (5) weaving on a loom to obtain the functional fabric. The composite functional fabric has the advantages of washing resistance, high temperature resistance and electromagnetic radiation resistance.