A water distributor downstream side inner ring and outer ring mounting and locating rack for an extra-large bulb-type tubular-turbine hydraulic generator set comprises a large rack shaped like the Chinese character 'jing' and a small rack shaped like the Chinese character 'jing' that are welded with steel. The ends of the large rack and the small rack are fixedly connected with the end surface of an inner ring and an outer ring on the downstream side of a water distributor, and the large and the small racks shaped like the Chinese character 'jing' are fixedly connected together via a bracket. The mounting and locating rack provided by the utility model fixes the inner ring and the outer ring of the water distributor together through the fixed connection of the end surfaces of the inner ring and the outer ring on the downstream side of the water distributor, so as to enhance the structural strength of the entire water distributor, ensure constant relative position of the inner ring and the outer ring during hoisting process, reduce mounting difficulty and improve mounting quality. In addition, the large rack and the small rack enhance the strength of the inner ring and the outer ring, ensure the roundness of the inner ring and the outer ring of the water distributor, reduce deformation during hoisting process, and further improve the mounting precision.