Abstract: The traditional buckling-restrained brace (BRB) has been widely adopted to enhance structural seismic performance. This achievement often comes with increased strength and stiffness requirements, which may limit their effectiveness in dissipating energy during strong earthquakes. A pioneering two-stage capacity-adjustable sacrificial-energy dissipation BRB (CABRB) is proposed. The concept and mechanical characteristics of the CABRB are introduced. Three types of sacrificial connectors for the CABRB are studied through quasi-static experiments, and the corresponding refined numerical models are established to discuss the key parameters influencing the mechanical behaviors of the connectors. The mechanical behaviors of the CABRB equipped with the sacrificial connector are validated through numerical simulations. The simulation results indicate that the sacrificial connector with circular-arc-shaped end apertures exhibits favorable capacity-adjustable characteristics. The thickness (t), height (h₁), and curvature radius (R) are identified as critical parameters affecting their mechanical behaviors. The CABRB exhibits excellent design flexibility and capacity-adjustable characteristics, making it promising for fulfilling the demands of multi-level seismic response control and energy dissipation.