Cu-based catalysts, especially co-sites of Cu0 and CuⅠ, are the best competitors for electrochemical CO2 fixation to produce multi-carbon (C2 + ) products. However, it is challenging to construct highly stable CuⅠ sites due to the changeability of its valence state and electronic structure in the electroreduction process, and the mechanism is also elusive. Herein, a 2D conductive CuⅡ-MOF film (CuⅡHHTP@Cu0) is prepared on Cu (100) foil by in-situ electrochemical assembly. After pre-reduction, the in-situ produced Cu2O clusters are confined in the cavities of the film created by the local breaking of the MOF framework to construct a unique CuⅠ-CuⅡHHTP@Cu0 catalyst, so that a novel strategy is proposed to stablize highly dispersed CuⅠ sites during electrochemical reduction, thus protecting the Cu2O clusters from further reduction and ensuring the coexistence of CuⅠ (111)-Cu0 (100) sites. As such, the current density of CO2 electrochemical reduction catalyzed by this catalyst exceeds 300 mA cm−2, the duration overs 50 h, and the C2 selectivity achieves 72.6 %. In-situ spectroscopy and theoretical calculations reveal that the optimized microenvironment of the CuⅠ (111) sites reduces the energy barrier of *OCCOH coupling, and Cu0 (100) sites increase the coverage of *CO, thus boosting the production of C2 products.