The invention provides a method for improving low-temperature impact toughness of a weld joint of a weld pipe welded in the manner of high-frequency straight welding, which comprises the step of carrying out thermal treatment on the weld joint of the weld pipe of which the pipe billet is welded in the manner of high-frequency straight welding, wherein the thermal treatment comprises annealing treatment and normalizing treatment after the annealing treatment; the temperature of the annealing treatment is 650-720 DEG C; the time of the annealing treatment is 5-20s; the temperature of the normalizing treatment is 1060-1100 DEG C; and the time of the normalizing treatment is 5-20s. In the method, the normalizing treatment is carried out on the weld joint of the weld pipe welded in the manner of high-frequency straight welding at the temperature of 1060-1100 DEG C which is 100 DEG C higher than the conventional normalizing temperature (30-50 DEG C higher than Ac3), thereby, the texture of the weld joint of the weld pipe is ensured to be fully austenitized, the difference between the texture of the weld joint and the texture of a parent metal can be greatly reduced, and the low-temperature impact toughness of the weld joint of the weld pipe is obviously improved.