Abstract: Fe-Ni-S alloy film was prepared on red copper foil by electrodeposition from a acidic bath containing boric acid as a buffer agent and sodium citrate as a complexing agent. The effects of the bath composition, and the deposition parameters on the surface morphology and the composition of the alloy coating were studied by SEM and EDS. As a result, a smooth coating with no crack and little stress was obtained from the plating bath by adding 2 g/L saccharin and 0.4 g/L 1,4-butynediol. The cathodic current density and the plating bath pH have little effect on the coating composition, but the temperature has great effect. Fe₇₃Ni_9.5S_17.5 film was prepared in optimized plating conditions, and XRD analysis showed that the coating structure is amorphous. The film has good soft magnetic performances with higher saturation magnetization (M_s≈876.25 kA/m) and lower coercivity(H_c≈4.96 kA/m) at room temperature. Cyclic voltammetry and the cathodic polarization curves indicated that thiourea can promote the co-deposition of Fe-Ni-S alloy.