In the process of extracting antimony by alkaline electro-deposition, problems such as cracking of the cathode deposited antimony, causing warping and shedding, occur due to insufficient interfacial bonding force between Sb and Fe, surface sandblasting pretreatment technology was proposed. The effects of the sandblasting pretreatment on the cathodic reduction and nucleation mechanism of antimony ions were systematically analyzed by combining cyclic voltammetry, steady-state polarization curves, and time-current transient curves. The results show that for the alkaline electro-deposition system of antimony, after sandblasting pretreatment of the iron-based cathode surface, the initial potential of the cathodic reduction reaction shifts to the left and positive. At the same overpotential, the current density is significantly increased compared to that without sandblasting treatment, and transfer coefficient and exchange current density are also enhanced. This indicates that the sandblasting treatment of the cathode surface can reduce the energy barrier of the cathodic reduction reaction of antimony ions, significantly increase the reduction reaction rate, and promote the three-dimensional nucleation process of antimony on the cathode surface, thereby obtaining a dense. well-shaped cathode antimony deposit layer. Further in-depth research was conducted on the influence of sandblasting particle size on the antimony electro-deposition process, and the optimal sandblasting particle size was determined to be 80 mesh. Under the condition, the cathode current efficiency is increased to 80.1%, the cell voltage is 2.031 V, the direct current power consumption per ton of antimony is reduced to 1674.76 kW·h/t, and the purity of cathode antimony reaches 98.81%.