The invention discloses a welding repair method for nuclear power equipment made of low-alloy high-strength steel. The welding repair method comprises the step: realizing a tempering process of a coarse grain region of a parent metal heat-affected region formed by a first-layer welding bead by welding heat circulation formed by a second-layer welding bead. By controlling the energy of a welding line, the impact absorbing energy of the coarse grain region of the heat-affected region of the obtained welded joint is equal to that of a conventional manufacturing process, so that the requirement for manufacturing quality can be completely met, and post-welding heat treatment is not needed.