The invention discloses a method for welding a ring crane corbel of a nuclear power plant. The method comprises the following steps that a box-shaped part of the corbel and a stiffened buried plate are welded and formed correspondingly, wherein according to the welding sequence of the box-shaped part of the corbel, an upper cover plate and a lower cover plate are assembled and welded with two boxside plates correspondingly, and an inner supporting plate is welded between the two side plates; an upper cover plate reinforcing stiffened plate is welded among the upper cover plate, the side plates on the two sides and the inner supporting plate; an inner concentric-square-shaped plate is wended among the lower cover plate, the upper cover plate and the side plates on the two sides; a box front baffle is welded among the inner supporting plate, the lower cover plate and the side plates on the two sides; the stiffened buried plate is composed of a back rib plate and a buried plate of the corbel; and overall assembling and welding of the corbel are carried out. According to the method, the welding amount of the part plates, the welding stress intensity, the specifications of the welded parts, the assembling machine welding space limiting conditions and the mutual constraint conditions of the part plates are analyzed, the prefabricating and assembling sequence of the ring crane corbelof the nuclear power plant is determined, and it is ensured that the prefabricated size of the ring crane corbel reaches the first pass yield of 100%.