The invention relates to a built-in buckling restrained brace connecting joint. The connecting joint comprises a connecting joint plate, core plate stiffening plates, a core plate and an outer wrapping pipe, wherein the core plate stiffening plates are fixed at the two ends of the core plate; the outer wrapping pipe is fixed at the peripheries of the core plate stiffening plates and the core plate; the core plate stiffening plates and the core plate extend out of the two ends of the outer wrapping pipe; gaps are preset in the connecting joint plate, and are matched with the end parts of the core plate stiffening plates; the core plate stiffening plates are arranged in the gaps in the connecting joint plate and fixed; meanwhile, the connecting joint plate and the core plate are fixed. Through the improvement on the buckling restrained brace connecting unit and the joint plate, the connecting joint has the advantages that the material is saved, the structure is simple and compact, and the mounting is convenient, the problem of crossed welding when the buckling restrained brace element and the joint plate are embedded or welded does not exist, and the safety of the connecting joint under the action of earthquake load is ensured.