The invention discloses a method of preparing large-size yttrium-system bulk by using YbBCO as filler metal by a braze welding method, which belongs to the technical field of superconduct bulk preparation. The method adopts a top seed crystal melting texture growth method for preparation by adding YbBCO filler metal, adopts a braze welding connecting technology to weld YbBCO bulk, carry out post-oxidation treatment of braze welding joints and recover the superconductivity of YbBCO and a joint section thereof to obtain the large-size yttrium barium copper oxide superconduct bulk. The YbBCO superconduct bulk with large size and complicated shape, which cannot be prepared by the traditional method, can be prepared by the method and has the superconductivity similar to that of single-domain bulk prepared by a top seed crystal melting texture method. The superconductivity of the high-temperature YbBCO superconduct bulk prepared by the invention can reach more than 70 percent of that of original bulk.