The cyclic voltammetry and potential step methods were used to investigate the electrochemical behavior of Fe2+ and La3+ in FeCl2-LiCl-DMSO and LaCl3-LiCl-DMSO systems on Pt, Cu and Ni cathodes. The electroreduction of Fe2+ to Fe is irreversible in one step,while the electroreduction of La3+ to La is quasi-reversible. The diffusion coefficient of La3+ in LaCl3-LiCl-DMSO system at 298 K was 3.1×10-6 cm2s-1. The diffusion coefficient and transfer coefficient of Fe2+ in FeCl2-LiCl-DMSO system at 298 K were 2.54×10-6 cm2*s-1 and 0.24, respectively. La-Fe alloy films containing La from 22.7% to 37.1% (mass fraction) were prepared by potentiostatic electrolysis on Cu substrates at a deposition potential from -1.750 to -2.450 V (vs SCE). The fine La-Fe alloy films were also obtained by pulse electrolysis at a pulse current densities from 2 to 6 mA*cm-2. The surfaces of these alloy films are smooth, adhesive and uniform, and have metallic luster.