The invention discloses a cable outer sleeve welding device. The welding device comprises a track, wherein a traveling unit is arranged on the track, a rotating unit capable of rotating around the central axis of the traveling unit is arranged on the traveling unit, the rotating unit is provided with a welding bracket and an angle adjusting system used for adjusting the inclination angle of the welding bracket relative to the horizontal plane, and the welding bracket is provided with a longitudinal seam welding system for realizing single segment outer sleeve welding and an annular seam welding system for realizing butt welding of two adjacent segment outer sleeves. According to the welding device, a matched welding device for the construction process of back mounting the outer sleeve to the cable body in a cable structure except a steel strand system is provided.