Driven by the goal of global carbon neutrality, electrocatalytic carbon dioxide reduction reaction (eCO₂RR) technology has become a research hotspot due to its potential to efficiently convert CO₂ into high value-added products, such as ethylene and ethanol. Cu-based catalysts become the core material under their unique electronic structure and C–C coupling ability. It is precisely designed by single atomic sites (SACs) and diatomic site catalysts (DASCs). Combined with the stabilizing effect of composite carriers (such as metal–organic framework (MOF) materials) on the Cu active site, the product selectivity and reaction kinetics were significantly improved. In situ characterization and computational simulation revealed the dynamic reconfiguration of Cu sites and the adsorption mechanism of *CO intermediates. This result confirms that low-coordination Cu sites promote C–C coupling through the Eley–Rideal (ER) pathway, and high-pressure/high-temperature conditions can regulate the reaction path. Despite outstanding laboratory performance, industrial applications still face low stability at high current densities, high-scale preparation costs, and system integration challenges. In the future, it is necessary to focus on the analysis of atomic-level reaction mechanisms, the development of intelligent response materials, and the coupling technology of photoelectric and electrocatalysis, combined with green power matching and carbon tax policy coordination, to promote the leapfrog development of copper-based catalysts from basic research to industrial carbon cycle technology.