The invention relates to an acidic coating super duplex stainless steel welding rod and belongs to welding material technology. The invention adopts 2507 duplex stainless steel wires as the welding core; the components and the weight percentages of the components of the welding rod coating are as follows: 30-40 of rutile, 3-7 of titanium dioxide, 15-20 of potash feldspar, 1-3 of phlogopite, 5-10 of marble, 16-20 of metal powder, 0.5-1.5 of rare earth fluoride, 2-3 of cryolite, 5-8 of chrome green, 0.5-1.0 of soda, and 1.5-3.5 of ferroalloy. The welding rod of the invention has the advantages, showed by the test results of manufacturability, metallographic observation, mechanical property and corrosion resistance, that the welding rod has extremely good welding technical property; electric arc is stable during welding, and spattering does not basically exist; the formation of weld joints is good; slag detachability is good; the manipulability of the welding rod is excellent; through metallographic observation, the content of ferrite in the structure of welding joints ranges from 40 percent to 60 percent, and the phase ratio can meet engineering application requirement; the weldedwelding joint has excellent mechanical property, and tensile strength can be more than 800 MPa; low temperature toughness is good; the stress corrosion resistance and pitting corrosion resistance of the welding joint are excellent.