The invention discloses a wire feeding system for a welding head. The wire feeding system comprises a wire feeding rod, a wire feeding rod support and an adjusting screw, wherein one end of the wire feeding rod support and the wire feeding rod are fixedly connected to be a whole at a predetermined angle, the other end of the wire feeding rod is fixedly connected with the adjusting screw, and thus the wire feeding rod is driven by the rotatable adjusting screw to rotate. The rotating angle of the wire feeding rod is small, so that it is convenient to control a welding wire to move in a small range, and accordingly the relative position between the welding wire and a molten pool is adjusted. The welding head is infinitely rotary, the wire feeding system on the welding head can adjust the relative position relations of the molten pool and the welding wire according to concrete working conditions of a circumferential weld joint around the welding head in the rotating process of the welding head, and thus the welding quality can meet the quality requirements of nuclear power products.