The invention relates to a method for preparing a vanadium nitride iron alloy. The method comprises the steps that a vanadium source, a carbonaceous reducing agent and iron powder are mixed and then pressed into bulk materials; the bulk materials are heated and subjected to a carbonization reaction, then the temperature rises 1300-1500 DEG C under the nitrogen atmosphere for a first-time nitridingreaction; and after heat preservation is finished, the temperature is reduced to 1100-1300 DEG C for a second-time nitriding reaction, and the vanadium nitride iron alloy is obtained after the reaction. According to the method for preparing the vanadium nitride iron alloy, the two-step nitriding method is utilized to prepare high-nitrogen vanadium nitride iron, and the vanadium nitride iron withthe nitrogen content being 14.0-15.5 wt% is prepared by adjusting the temperature and the nitrogen flow rate; and at the same time, the purity of products is effectively improved, the contents of impurity elements such as oxygen and carbon are reduced, and vanadium nitride iron products with the greater proportion and the better quality are obtained. The method for preparing the vanadium nitride iron alloy is simple in process, common in used equipment and low in energy consumption in the preparing process of the vanadium nitride iron, and has good application prospects.