NOVELTY - Vanadyl sulfate is extracted with acidic extraction agent, stripped using sulfuric acid and purified. Resultant material is extracted using neutral oxygen-containing ester and acidic phosphorus-containing compound as extracting agent and stripped. The pH value of resultant mixture is adjusted, stripped, organic phase of vanadyl sulfate solution is adsorbed, to obtain high-purity vanadium sulfate solution. Resultant solution is pickled, washed, subjected to high-temperature treatment, heated, cooled, and filtered, to obtain vanadium redox flow battery electrolyte.    USE - Preparation of vanadium redox flow battery electrolyte (claimed).    ADVANTAGE - The vanadium redox flow battery electrolyte with high purity is prepared by economical process.    DETAILED DESCRIPTION - Edulcoration agent is added to the stock solution, impurities are removed by filtration using aluminum salt, magnesium salt and calcium salt (excluding silicate, chromate and phosphate), further metal impurities are removed using carbonate, extracted with 30-40 %mass quaternary ammonium salt as alkaline extraction agent and kerosene as diluent, stripped with weak alkaline solution of ammonium chloride as stripping agent and pentavalent vanadium solution is purified. Reductant is added vanadate precipitate, acidity is adjusted, vanadate is reduced to vanadyl sulfate using amoxicillin hydrazine as inorganic material, oxalic acid as organic compound, and sulfuric acid as inorganic acid and pH of the solution is adjusted to less than 1 with acetic acid as organic acid, to obtain vanadyl sulfate. The vanadyl sulfate is extracted with acidic extraction agent, stripped using sulfuric acid having concentration of 3-4 M, and purified. Resultant material is extracted using neutral oxygen-containing ester and acidic phosphorus-containing compound as extracting agent, tributyl phosphate as synergistic extraction agent and sulfonated kerosene as diluents, and stripped using sulfuric acid having concentration of 3-4 M as stripping agent. The pH value of the resultant mixture is adjusted to 2-3 using ammonia, sodium hydroxide, calcium carbonate or barium carbonate, stripped, and organic phase of vanadyl sulfate solution is adsorbed using activated carbon, to obtain high-purity vanadium sulfate solution. Resultant solution is pickled, washed, subjected to high-temperature treatment, organic and inorganic impurities are removed, activated carbon powder is added, heated, cooled, and filtered, to obtain vanadium redox flow battery electrolyte. The ratio of aluminum salt and silicate is 1:1.1. The ratio of magnesium salt and chromate is 1:1.1. The ratio of calcium salt and phosphate is 1:1.1.