The invention belongs to the technical field of pharmaceutical chemical intermediates, and provides a preparation method of an allyl aromatic compound. The preparation method comprises the following steps: by using benzyl chloride and derivatives thereof as raw materials, reacting with an allyl silane compound in a non-aqueous organic solvent under the effect of metal catalysts and additives, and then converting into the allyl aromatic compound under the effect of protonic acid. The preparation method disclosed by the invention has the advantages of being low in raw material prices, less in reaction step, mild in reaction condition, environmentally friendly, convenient for operation and high in reaction yield.