The invention provides a method for preparing estra-4,9-diene-3,17-dione. The method comprises the steps of: performing mixed acid anhydride preparation, a Grignard reaction, a ring closure reaction,a hydrolysis and a ring closure reaction in order by using a compound having a general formula I as a reaction raw material, and preparing the compound having a structural formula V. A synthetic routeof the compound having the structural formula V is shown as the specification. The preparation method of the estra-4,9-diene-3,17-dione provided by the invention has the advantages of simple operation step, low cost of raw materials, small amount of an organic solvent, easy post-treatment, and easy amplification production in a synthetic process.