An electrolyte was prepared using ammonium metavanadate (AMV) to apply in the all-vanadium redox flow battery (VRFB). The component and composition of the prepared electrolyte by AMV were analyzed by X-ray diffraction (XRD) and inductively coupled plasma (ICP). It was confirmed from the analysis results that the component was almost the same as that of vanadyl sulfate and the composition was almost the same as that of prepared by 2.1mol of the vanadyl sulfate dissolved in 3M H2SO4. The cell performance of VRFB using the prepared electrolyte by AMV was measured at current density of 60mA cm-2. The efficiency of VRFB using the prepared electrolyte by AMV was 97.66%, 86.31%, 84.30% for an average current efficiency, average voltage efficiency and average energy efficiency, respectively. It was expected that the prepared electrolyte by AMV was usable as the electrolyte of VRFB from the viewpoint of the cell performance.