Cu-based catalysts are widely employed in the electrocatalytic CO₂ reduction reaction (CO₂RR) toward multi-carbon (C₂₊) products due to their unique electronic structures. However, Cu-based catalysts are prone to reconstruction under working conditions. Self-reduction and undesirable reconstruction have limited the activity and selectivity of these catalysts. Understanding their reconstruction behavior is crucial for elucidating reaction mechanisms and rationally designing catalysts. In this study, Br-doped Cu-base catalysts were employed to investigate the influence of dopants on catalyst surface reconstruction during CO₂RR. Characterizations confirmed that during CO₂RR, partial Br⁻ leached from the precursor, while residual bromide ions in the Cu matrix created a bromine-rich environment on the catalyst surface, stabilizing Cu⁰/Cu⁺ active sites. The reconstructed catalyst exhibited superior selectivity for C₂₊ products and higher current density. In situ characterization and theoretical calculations demonstrated that the interaction between Br and Cu atoms suppressed complete Cu reduction. Furthermore, the asymmetric coupling pathway via *CO and *CHO intermediates dominated C₂₊ product formation, with significantly reduced Gibbs free energy of key intermediates compared to undoped CuO. Notably, halogen doping was validated as a universal strategy—Cu–Cl and Cu–F catalysts similarly enhanced C₂₊ production while exhibiting analogous reconstruction behavior. This study provided deep insights into catalyst surface reconstruction and offered effective strategies for designing high-performance catalysts for CO₂RR.