The invention relates to a high-tenacity wear-resisting overlaying alloy welding wire for a cold-rolling support roller, and the overlaying alloy welding wire provided by the invention has excellent tenacity and suitable hardness. The alloy welding wire comprises the following chemical components by weight percent: 0.2-0.4% of C, 1.0-2.0% of Mn, 0.5-1.5% of Si, 3.0-6.0% of Cr, 0.5-2.0% of Mo, 1.0-3.0% of Ni, less than or equal to 0.02% of P, less than or equal to 0.01% of S, and impurities, wherein the impurities comprise mineral substances and alloy powder; the mineral substances, the content of which is 2-5%, comprises one or more than one of CaF2, CaCO3, Na3SiF6 and LiF2; the alloy powder, the total content of which is 0.3-2.0%, comprises one or more than one of vanadium, tungsten, niobium, titanium, aluminum, and the like; and 0.1-0.5% of rare earth is additionally added. The welding wire is matched with a suitable welding process, thereby acquiring the hardness of HRC (Rockwell hardness) 48-53. A low-carbon steel belt is used for wrapping the alloy powder and the mineral substances and then rolling and drawing are performed, thereby forming the welding wire. A reasonable component design is matched with HJ107, grains are refined and sulfur-removing components are added, so that the high-tenacity wear-resisting overlaying alloy welding wire is free from hot crack in an overlaying process, has the hardness and tenacity suitable for cold-rolling rollers, and meets the demand of overlaying a cold roller.