The invention discloses a bismuth-free stainless steel flux cored wire gas shielded welding technology for connecting pipes. According to the technology, a welding manipulator is transformed, a connecting plate provided with a T-shaped groove is fixed at one end of a cross beam of the welding manipulator, a transition frame provided with a slide rail is clamped through the T-shaped groove, a mechanical arm swing mechanism is installed on the slide rail, a cross arm beam is mounted at the bottom of the mechanical arm swing mechanism, an extension arm is fixed at the bottom of the cross arm beam, the bottom of the extension arm is connected with a fastener, a welding torch locking block is installed on the fastener, and a welding torch is placed in the welding torch locking block. By means of the welding device, parameters such as welding currents, voltages, welding wire extension and weld bead lifting capacity are matched, the bismuth-free stainless steel flux cored wire gas shielded welding technology capable of performing stable welding is developed and applicable to circumferential bismuth-free stainless steel flux cored wire gas shielded build up welding and butt welding of regular connecting pipes, the welding process is stable, formed welding seams are attractive in appearance, and the productivity is improved by 6-7 times than that of A-GTAW.