Preparation method of ammonium polyvanadate

The invention relates to a preparation method of ammonium polyvanadate. The method comprises the steps that under the acidic condition, leaching liquor containing vanadium makes contact and is reacted with crystallizing agents, the crystallizing agents comprise the crystallizing agent A and the crystallizing agent B, the crystallizing agent A adopts water-soluble ammonium salt and/or ammonium hydroxide, and the crystallizing agent B adopts one or more of formaldehyde, acetaldehyde and propionaldehyde. The preparation method of the ammonium polyvanadate is conducted at the normal temperature, the reaction temperature does not need to be controlled, and the reaction time is short. Therefore, the preparation method of the ammonium polyvanadate has the advantages of being simple in technology and low in energy consumption.