The electrochemical reaction mechanism and electrocrystallization process of Cu on copper electrode in the eutectic NaCl-KCl-CuCl molten salt were investigated by means of cyclic voltammetry, chronopotentiometry and chronoamperometry technique at 710 C. The results show that the electrochemical reaction process of Cu is a quasi-reversible process mix-controlled by Cu + diffusion rate and electron transport rate; the electrochemical reduction mechanism is Cu + +e→Cu; the electrocry stallization process of copper is an instantaneous hemispheroid three-dimensional nucleation process; the Cu + diffusion coefficient is 4.3×10 4 cm 2 ·s 1 under the experimental conditions. The electrochemical reaction mechanism and electrocrystallization process of Cu on copper electrode in the eutectic NaCl-KCl-CuCl molten salt were investigated by means of cyclic voltammetry, chronopotentiometry and chronoamperometry at 710 C. The results show that the electrochemical reaction process of Cu is a the electrochemical reduction mechanism is Cu + + e → Cu; the electrocry stallization process of copper is an instantaneous hemispheroid three-dimensional nucleation process; the Cu + diffusion coefficient is 4.3 × 10 4 cm 2 · s 1 under the experimental conditions.