The simultaneous electrodeposition of dysprosium and terbium on platinum electrode in 1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIMBF4) ionic liquid was investigated. The cyclic voltammetry, chronoamperometry and constant electrolysis experiments have been employed to examine the electrochemistry of dysprosium and terbium ions in 0.01 mol/L DyCl3-0.023 mol/L TbCl3-0.27 mol/L LiCl-EMIMBF4 ionic liquid. The electrochemistry experiments indicated that the reduction of dysprosium and terbium ions in 0.01 mol/L DyCl3-0.023 mol/L TbCl3-0.27 mol/L LiCl-EMIMBF4 ionic liquid was an irreversible process and simultaneous process. In 0.01 mol/L DyCl3-0.023 mol/L TbCl3-0.27 mol/L LiCl-EMIMBF4 ionic liquid the diffusion coefficient of the diffusion process of species which controlled the total electrochemical reduction process have been determined to be (3.79–7.07) × 10−6 cm2/s from cyclic voltammetry and chronoamperometry results. XRD spectrum of constant electrolysis samples showed that dysprosium and terbium deposits were obtained.