Abstract: The purified alkaline vanadium solution obtained from the process of sodium roasting for vanadium slag was used as the raw material in this experiment,and the content of V and Na,and impurities content of Si and P were analyzed.A new process of vanadium precipitation under acidic condition was investigated using melamine as precipitant which substitutes for the ordinary ammonium agents such as ammonium sulfate and ammonium carbonate,etc.,and the effect of Na content in the solution on vanadium precipitation was also studied.The results show that powdery V₂O₅ satisfying the standard requirements is obtained after 3 hours of calcination at 500 ℃ with the precipitate as raw material,which is prepared at 0.3 of mole ratio of melamine to vanadium,pH = 2. 0,90 ℃ of precipitation temperature for 45 min. The precipitation rate of vanadium at the optimum conditions mentioned above is more than 98%,and the content of remaining vanadium and NH₄⁺ in the wastewater keeps at an extremely low range,simplifying the subsequent treatment process for waste water. This method is suitable for the aqueous solution where n[Na]/n[V]≤5.0 （mole ratio） and has an excellent test result.