A novel two-stage buckling-restrained brace (TS-BRB) has been proposed to enhance the performance of conventional buckling-restrained braces (BRB), particularly addressing the problem that conventional BRB cannot provide lateral resistance and energy dissipation capacity to the structure after failure under the action of major-after shocks. The energy dissipation unit of TS-BRB consists of three Q235 steel plates in series with tapering cross-section along the longitudinal axis. The energy dissipation section in the middle plays the role of energy dissipation firstly during earthquake, and if this section breaks, the limit slot in the restraint unit ensures the rest of the energy dissipation section keeps working, thus giving TS-BRB a higher energy dissipation capacity than conventional BRB. The slipping distance of TS-BRB is limited by varying the length of the limit slot, enabling the brace to meet the requirements for structural damping design. Test results demonstrate that the hysteresis curve of the TS-BRB is saturated and the shape of the hysteresis curve is consistent with theoretical expectations. TS-BRB exhibits evident two-stage energy dissipation characteristics, with the end energy dissipation section continuing to operate after the middle energy dissipation section breaks. The additional accumulated energy dissipation after the fracture is 138.41% of that before the fracture. The TS-BRB provides a solution to the issue of conventional BRBs losing load-bearing and energy-dissipation capacity immediately after fracture and offers greater energy dissipation reserves for the structure. Finally，a numerical model was established in ABAQUS，which demonstrates that the hysteretic curve of numerical simulation agrees well with that of experiment．