The invention discloses a method for forming an inclined Y-shaped crossed rib structure through wire and arc additive manufacturing, and relates to the field of metal additive manufacturing. The forming method is characterized by comprising the following steps that S1, one axial end of a short edge is connected with the middle of a long edge, and a model of an inclined Y-shaped cross rib is established; S2, chamfering transition is carried out on the outer edge and the opening end of the side wall of the bottom plane of a Y-shaped cross rib, and an extending section is added; S3, equal-thickness slicing is carried out on the Y-shaped cross rib in the height direction, a weld joint is designed on the upper surface of each layer of slice, and the position of the weld joint of each layer of slice is the same; S4, a rectangular plate-shaped base plate is selected, and the base plate is horizontally placed; S5, welding is sequentially carried out on all the layers of slices in the height direction of the Y-shaped cross rib on the upper surface of the base plate; and S6, machining removing is carried out on the welded Y-shaped cross ribs, and finally forming is achieved. According to themethod, the situations that in an existing process of forming an inclined Y-shaped cross rib through wire and arc additive manufacturing, poor lap joint quality, incomplete fusion and other technicalproblems are prone to occurrence at the intersection position are avoided.