Abstract: This article develops tandem automatic welding system for pipeline according to the principle of tandem welding technology, develops efficient welding technology about "Internal welding machine for root welding and double wire automatic welding for filling and capping welding". Experiments indicate tandem automatic welding technology can avoid defects existing in pipeline welding construction effectively to ensure the welding quality, such as incomplete fusion, stomata, incomplete penetration, pipeline welding discontinuous and undercut. At the same time, it can increase the weld single-layer filling thickness from2-3 mm to 4-6mm, and it can get beautiful welding gap, excellent mechanical properties. This technology can meet pipeline construction on the welding requirements of high efficiency, and has the application value and guiding significance for construction of oil and gas field welding of pipeline.