The invention discloses a welding tool for a one-piece wire tube evaporator. The welding tool comprises a base, baffle blocks, self-locking insertion pins, pressure plates, comb-shaped strips and a short tube positioning needle, wherein the base is a rectangular framework structure, and a centre plate is arranged in the middle of the base for dividing the base into left and right areas; the baffle blocks and the self-locking insertion pins are symmetrically distributed at the two sides of each area; the self-locking insertion pins are connected to the baffle blocks; the pressure tubes are arranged at upper and lower ends of the base for fixing a wire tube; and the comb-shaped strips for fixing steel wires are symmetrically distributed at the two sides of the center of each of the left and the right areas of the base. The welding tool overcomes the defect that steel wires are positioned asymmetrically in the prior art, can realize the purpose that one welding tool produces the one-piece wire tube evaporator, is high in production efficiency, is simple in design, is reasonable in structure, and is suitable for being used in mass production of one-piece wire tube evaporators.