The invention relates to the field of the cell manufacturing and especially relates to a method of preparing the electrolyte of the vanadium ion liquid cell, making the 1:1 thin vitriol from the thick vitriol, adding the trioxid bi-vanadium and then the five-trioxid bi-vanadium to get the vitriol oxide vanadium; adding the Na2SO4, emulsification agent OP and other additive, placing the vitriol oxide vanadium at the cathode of the electrolytic cell and the same ion intension at the anticathode and electrolyse, getting the vitriol electrolyte used for vitriol batteries which includes half quadrivalence vanadium and half tervalent vanadium. The invention simplyfy the equipment of vitriol batteries and chemical procedure, enhance the work efficiency, extend the use time of the functional materials of vitriol batteries, such as the electrode and the dissepiment, needn't change the electrolyte of the anode, avoid wasting raw material, avail the producing by large scale.