NOVELTY - Preparing vanadium electrolyte, comprises: adding a cleaning agent to a source liquid and then filtering to obtain vanadate precipitate; adding vanadate precipitate and then heating, adding ammonium metavanadate to the heated mixture to obtain precipitate and then dissolving, adding vanadyl sulfate, ammonia and sulfuric acid to the mixture and then regulating pH, extracting the reduced mixture and then reacting to obtain a raffinate, regulating pH value of the raffinate; and removing residues to form a vanadyl sulfate solution, processing the solution and then filtering.    USE - The method is useful for preparing high concentration vanadium electrolyte (claimed), which is useful for a vanadium flow battery.    ADVANTAGE - The method is capable of economically preparing the high concentration vanadium electrolyte with excellent purity.    DETAILED DESCRIPTION - Preparing high concentration vanadium electrolyte, comprises: (1) adding a cleaning agent to a source liquid containing high content of vanadium and comprising silicate and chromium radicals and aluminum salt, magnesium salt and calcium salt, and filtering the mixture to remove aluminum salt, magnesium salt and calcium salt at a pH of 10-11 and then precipitating to obtain a vanadate precipitate, where a weight ratio of silicate radical and chromium radical is 1:1, and a weight ratio of magnesium salt and calcium salt is 1:1.1; (2) adding vanadium to the source liquid after the filtering process, precipitating vanadate from the liquid using acid and alkali, regulating pH of the liquid using sulfuric acid at a temperature of 5 degrees C to 2-2.5, heating the mixture at a temperature of 98 degrees C, adding ammonium metavanadate to the heated mixture to obtain a precipitate, dissolving the precipitate with water, adding ammonium hydroxide to regulate pH value to be 9, and carrying out alkaline precipitation process of the mixture to obtain ammonium metavanadate precipitate, where the weight ratio of ammonium metavanadate and vanadium is 1:2, and the weight ratio of ammonium hydroxide and vanadium is 1.2:1; (3) adding oxalic acid as a reducing agent to the vanadate precipitate and then regulating acidity, adding vanadyl sulfate to the mixture, further adding ammonia and sulfuric acid as inorganic acid to the mixture, regulating pH of the mixture to be less than 1 using an organic acid such as acetic acid, and reducing vanadyl sulfate content from the mixture; (4) adding an acidic extraction agent to the reduced mixture obtained from the step (3) and then extracting with 4 M of sulfuric acid, purifying the mixture with phosphorus compound as an extracting agent, adding tributyl phosphate and sulfonated kerosene type diluent to the mixture at a weight ratio of 1:1, reacting the mixture with ammonium hydroxide, sodium hydroxide, calcium carbonate or barium carbonate to obtain a raffinate, regulating pH value of the raffinate to 2-3, and further extracting the raffinate; and (5) removing surface residues of an organic phase from the extract to form a vanadyl sulfate solution, washing the solution by activated carbon and then further washing with an acid and water, processing the solution at high temperature to remove organic and inorganic impurities, and heating the processed solution and then cooling and filtering to obtain the high concentration vanadium electrolyte.