This equipment is mainly comprised of a integrated gantry plate joining rack, a logistics delivery system, a welding system, a data monitoring system, a centralized lubrication system, an electrical control system, a beveler, a welding tractor and power supply, and the power supply for the manual metal-arc welding at the overhaul position. The overall range of the equipment is 10m & 20m. Plates are joined and welded with hydraulic keyboard pressing at the front, water-cooled copper bush packing forming slot at the back and twin-wire gas shielded arc welding for one side welding with back formation. The process of one side welding with back formation avoids turning of work pieces in welding by two sides, saves field, reduces labor intensity, improves welding efficiency, and realizes streamlined welding. Various parts of the one-side automatic welding workstation can cooperate; PLC centralized control mode is adopted; it features compact design, great automation and easy operation. With complete auxiliary mechanisms, the machine can deliver excellent performance.