The invention relates to a method for preparing geopolymers by taking stone coal vanadium extraction tailings as main raw materials. The technical scheme is as follows: the method adopts the following raw materials in percentage by weight: 55-76% of stone coal vanadium extraction tailings, 1-5% of hydrated lime, 0.3-2% of anhydrous sodium sulfate, 10-16% of metakaolin, 6-10% of sodium hydroxide and 6-13% of silica fume. The preparation method disclosed by the invention comprises the steps of firstly, uniformly mixing the stone coal vanadium extraction tailings and an activating agent, standing, calcining, and performing mechanical vibration milling to obtain activated slag; then, adding metakaolin and sand, and stirring; finally, adding a liquid alkali activator prepared from sodium hydroxide, silica fume and water, stirring, forming, aging and curing to prepare the stone coal vanadium extraction tailing geopolymers. The method disclosed by the invention is simple in process, low in cost, relatively small in energy consumption, high in tailing utilization ratio and environment-friendly; the prepared geopolymers are relatively high in compression strength, strong in dry shrinkage resistance, good in permeability resistance and high in durability, and have a good curing effect on heavy metal ions.