Abstract: VOSO₄ used for vanadium battery was prepared by reduction of high purity V₂O₅ with H₂O₂,and the preparation technology and reaction mechanism were studied.The enthalpy and Gibbs free energy change of the reaction for preparing VOSO₄ were calculated,and the charge and discharge performance testing were performed using the prepared VOSO₄ as active material of vanadium battery.The results show that it's an exothermic reaction for VOSO₄ formation and the dissolution of V₂O₅ is promoted by the reaction.This technology is characteristic of simple,green and environment-friendly with the best mole ratio of V₂O₅:H₂O₂:H₂SO₄=1:1.2~1.4:2.4~2.5.The V⁴⁺ content in the obtained VOSO₄ accounts for 99.66% of total vanadium amount,with V⁵⁺ occupying 0.34%.The prepared VOSO₄ has a good charge and discharge performance,which can be used as active material of vanadium battery electrolyte.