The work aims to study the effect of the additive ammonium cerium sulfate on displacement silver plating on copper substrate and improve the understanding of the heterogeneous nucleation mechanism during displacement plating. The ammonium cerium sulphate of different concentrations for silver plating was studied by cyclic voltammetry (CV), Tafel curve, electrochemical impedance spectroscopy (EIS), electrochemical noise (EPN) and scanning electron microscope (SEM). As the concentration of ceric ammonium sulfate increased, the amount of Ag[(NH3)2]+ increased, thus resulting in larger resistance in cathode reduction. The adsorption of Ce4+ on the copper surface hindered the oxidation reaction of copper and the reduction reaction of silver ions. The exchange current density of anode and cathode were decreased by 33.9% and 13.4%, respectively. When the concentration of ceric ammonium sulfate reached 6 mg/L, the capacitive reactance arc in the middle of the EIS was significantly increased, so the effect of ceric ammonium sulfate on the anode was greater than that of the cathode. Electrochemical noise time-domain signal and SEM image displayed that the crystalline EN with large potential drift corresponded to the loose and uneven structure of silver deposit, while EN with small potential drift corresponded to the dense layer. The energy distribution plot (EDP) based on wavelet transformation showed that the accumulated relative energy in region B and C decreased, while the energy of region A increased significantly with the increase of ceric ammonium sulfate concentration. Ce4+ can realize dense and flat silver layer structure by forming adsorption layer of different thickness at the pit sites and protrusion sites in silver-plating bath with ceric ammonium sulfate. The ceric ammonium sulfate can inhibit the cathode and anode in the process of silver plating, so the control step of silver deposition system changes from diffusion-control through mixing control to activation control.