The invention relates to electrolytic plating assistant for hot dip galvanizing of a steel wire. Electrolytic plating assistant comprises the following components: 30-220 g/L of zinc chloride, 0-150 g/L of potassium chloride, 0-150 g/L of sodium chloride, 2-90 g/L of ammonium chloride, 0-100 g/L of boric acid, 0-70 g/L of acetic acid, 1-25 g/L of sodium fluoride, 2-50 g/L of cerium chloride, 0-50 g/L of potassium fluozirconate, 0-50 g/L of methanol, 0.5-20 g/L of hydrogen peroxide and the balance of water. The electrolytic plating assisting method comprises the following steps: washing with alkali, removing oil, washing with water, washing with acid to remove rust, washing with water, activating with weak acid, electrolyzing to assist plating, drying, and purifying the electrolytic plating assistant. The method can reduce the generation of AlCl3, prevent skip plating and reduce the generation of smoke dust. The electrolytic plating assistant has the characteristic of relatively high melting point, and thus, can increase the drying temperature and shorten the drying time. The dried plating assistant has the characteristics of low brittleness, high compatibility with electrogalvanizing, and low tendency to shedding.