NOVELTY - A vanadium electrolyte preparing method involves carrying out primarily hetero-vanadium precipitation, preparing high pure quadrivalent vanadyl sulfate solution comprising quinquevalent vanadium acid sodium solution, followed by adding raw liquid with impurity-removing agent to remove vanadium content in liquid to form a precipitate. The precipitate is filtered to remove port. The pH of the resultant liquid is adjusted by using aluminum salt, magnesium salt and calcium salt with vanadium silicate, chromium and phosphate impurity anion. The pH of the resultant liquid is adjusted.    USE - Method for preparing vanadium electrolyte for use in all-vanadium redox flow battery.    ADVANTAGE - The method enables preparing vanadium electrolyte with high purity, mild reaction and high concentration in a simple and inexpensive manner.    DETAILED DESCRIPTION - A vanadium electrolyte preparing method involves carrying out primarily hetero-vanadium precipitation, preparing high pure quadrivalent vanadyl sulfate solution comprising quinquevalent vanadium acid sodium solution, followed by adding raw liquid with impurity-removing agent to remove vanadium content in liquid to form a precipitate. The precipitate is filtered to remove port. The pH of the resultant liquid is adjusted to 1-8, preferably 9 by using aluminum salt, magnesium salt and calcium salt with vanadium silicate, chromium and phosphate impurity anion. The pH of the resultant liquid is adjusted to 10-11 by using carbonate and vanadium sulfide liquid metal removed impurity cations, maintaining aluminum and silicate at a mole ratio of 1:1-1:1.2, magnesium and chromium at ratio of 1:1-1:1.2, calcium salt and phosphate at a mole ratio of 1:0.7-1:1.2. The resultant liquid is precipitated by adding vanadium after removing impurity precipitation agent to form precipitation product. The precipitation product is subjected to liquid separation carried out using weak acid ammonium, acid ammonium and alkaline deposition to form vanadate crystal deposit, and other impurities. The pH of the resultant liquid is adjusted to 5 by adding ammonium chloride, and using sulfuric acid to adjust acidity to 2-2.5. The resultant liquid is heated at 95-100 degrees C to obtain ammonium metavanadate precipitate. The precipitate is dissolved in water to obtain mixture. The pH of mixture is adjusted to 9 using ammonia water, followed by controlling ammonium chloride and vanadium at a mass ratio of 1.5:3, and ammonia water and vanadium at a mass ratio of 1-1.5:1, reducing by adding reducing agent in vanadate precipitate, adjusting acidity, reducing vanadate to a vanadyl sulfate, controlling hydrazine hydroxylamine as inorganic and organic materials, oxalic acid as a reducing agent, sulfuric acid as inorganic acid, and acetic acid as organic acids. The pH of the resultant solution is adjusted to less than 1, followed by reduction of a vanadyl sulfate ammonium metavanadate, extracting vanadyl sulfate by using acidic extracting agent to obtain extract, performing 3-4 M sulfuric acid extraction, purifying vanadyl sulfate solution, using neutral oxygen-containing compound and acid phosphorus-containing compound as extracting agent, 30-40% phosphate ester as extracting agent, using 5-10% tributyl phosphate esters as synergist, sulfonated kerosene as diluent, and 3-4 M sulfuric acid as stripping agent, controlling extraction phase ratio of 1:1, carrying out sulfuric acid extraction by using extracting agent to obtain raffinate. The pH of the raffinate is adjusted to 2-3 by using ammonia water, sodium hydroxide, sodium carbonate, calcium or barium carbonate, followed by extracting for 4-6 times, using activated carbon to absorb vanadyl sulfate solution surface residual organic phase to prepare high pure vanadyl sulfate solution. The activated carbon is washed by acid washing, followed by carrying out high temperature process, removing organic and inorganic impurities after adding the activated carbon powder into extracting solution. The extracting solution is heated, cooled and filtered to obtain a finished product.