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The electrochemical CO2reduction over Cu catalysts has shown great potential in producing a wide range of valuable chemicals, but it is still plagued by a poor controllability on product distribution. Herein, we demonstrate an effective regulation of CO2reduction paths through a preanodization treatment of Cu foil electrodes in different electrolytes. The Cu electrode exhibits a superior C1and C2+product selectivity after being preanodized in NaClO4(Cu-NaClO4) and Na2HPO4electrolyte (Cu-Na2HPO4), respectively. Combined with in situelectrochemical Raman, ATR-SEIRAS, and SEM characterizations, the preferential C1path is due to the deposition of many Cu nanocrystals with dominant Cu(111) facets on the Cu-NaClO4electrode. In contrast, the preferential C2+path over the Cu-Na2HPO4is attributed to formation of a unique Cu nanodendritic morphology, which strengthens the *CO intermediate adsorption and induces an environment of low local H2O/CO2stoichiometric ratio, thus facilitating C–C coupling for C2+production. Our findings may shed light on the rational control of the CO2reduction path through engineering of the Cu surface structure.