The invention provides a high-reliability vanadium ion electrolyte, which is composed of vanadium sulphate, sulfuric acid, water and an additive, wherein the additive comprises at leas one material selected from the group consisting of an alkali metal salt, a hydroxyl-containing material and a surfactant. The high-reliability vanadium ion electrolyte provided by the invention, the deposition of V (V) and the oxidization of V (II) are effectively controlled by adding a novel additive composition into vanadium ion electrolyte and using the synergistic effects among the components of the additive, the stability of the electrolyte is greatly improved, and the charge and discharge properties and circulation stability of a vanadium battery effectively are improved by applying the vanadium ion electrolyte obtained to the vanadium battery.