Abstract: To clarify the collaborative working mechanism between the asynchronized parallel double-stage buckling restrained brace (APDBRB) and reinforced concrete frame structures, this study conducted seismic performance tests on Reinforced concrete (RC) frame substructures equipped with APDBRB. Through low-cycle reversed loading tests on APDBRB components and quasi-static tests on substructures with APDBRB, the mechanical behavior of this novel brace and its collaborative working mechanism with the primary structure were systematically investigated. The results indicate that, APDBRB exhibits asynchronized double-stage working characteristics and can form an effective collaborative energy dissipation mechanism with RC frames; When the APDBRB deformation reaches its second-stage activation deformation of 10 mm and the substructure deformation reaches the preset threshold of 16 mm, the second-stage core of APDBRB is effectively activated, achieving significant secondary enhancement of both lateral stiffness and load-bearing capacity of the substructure. When the substructure deformation reaches 52 mm, the horizontal load-carrying capacity decreases to 78% of the peak value, and the test is terminated. This study validates the effectiveness of APDBRB in improving the seismic performance of RC frames and provides experimental evidence for multi-stage seismic mitigation design and engineering applications.