Vanadium is a rare chemical element and it primarily comes from the by-product of other minerals. In this study, the material source mainly comes from vanadium-rich aluminum slag. This experiment aims to separate vanadium and other impurities, such as aluminum and zirconium. First, the slag was dissolved in the sodium hydroxide solution at pH value 13, and part of the alumina was precipitated. After removing the precipitation, the strong acid cation exchange resin, Dowex® G26, was added to eliminate the remaining impurities. In this procedure, the parameter of reaction time, the mass of ion exchange resin and pH value were supplied. Moreover, the adsorption isotherms described by means of the Langmuir and Freundlich isotherms were used to investigate the ion-exchange behaviors of vanadium. To sum up, this study will provide the best conditions of ion exchange to get high purity about 95% of vanadate.