An ellagic acid preparation method employing tara powder includes that tara powder is fully dissolved in water and filtered, the filter residue is discarded, and then sodium hydroxide is added to the filtrate, and the filtrate is transferred to sodium bicarbonate solution for standing to obtain the solution after hydrolysis; hydrogen peroxide, sodium persulfate or ammonium persulfate is added to the solution after hydrolysis; meanwhile, air is inflated into the solution, and then acetic acid is added to the solution and mixed evenly, the solution is filtered, the filter cake is washed by water and dried to obtain crude ellagic acid product; pyridine is added to the crude ellagic acid product for extraction, the extract liquid is condensed to saturated state, the extract liquid is cooled to normal temperature for crystallization, the reaction liquid is filtered to obtain the filter cake which is washed by water and dried to obtain light yellow ellagic acid. The invention provides a new method for ellagic acid preparation, points out a new industrialization direction of the tara industrial development, also has simple operation, low equipment level requirement and avoids using large quantity of strong acid and solvents in prior art.