NOVELTY - Preparing dehydroepiandrosterone comprises performing oximation reaction by adding e.g. dehydropregnenolone acetate to a reaction tank, cooling, separating, centrifuging, performing Beckmann rearrangement hydrolysis reaction by adding e.g. dehydropregnenolone acetate oxime, heating, reacting, cooling, washing, concentrating, separating, centrifuging, performing hydrolysis reaction by adding e.g. crude product of dehydroepiandrosterone acetate, refluxing e.g. dehydroepiandrosterone acetate, cooling, adding activated carbon, refluxing, filtering, concentrating, cooling, centrifuging and drying.    USE - The method is useful for preparing dehydroepiandrosterone.    ADVANTAGE - The method is simple, ecofriendly, produces high product yield, and ensures mild reaction conditions and low production cost.    DETAILED DESCRIPTION - Preparing dehydroepiandrosterone comprises (i) performing oximation reaction by adding dehydropregnenolone acetate, sodium acetate and absolute ethanol in a ratio of 1:(1.2-1.5):(4-4.5) to a reaction tank, cooling to 40 plus minus 5 degrees C, adding water (4 times), separating, centrifuging, and drying to obtain dehydropregnenolone acetate oxime; (ii) performing Beckmann rearrangement hydrolysis reaction by adding dehydropregnenolone acetate oxime, trichloromethane, phosphorus pentoxide, hydrochloric acid and water in a ratio of 1:(6-6.5):(0.8-1):(0.5-0.5):(6-7), heating to 60 plus minus 2 degrees C, reacting for 4 hours, cooling to 5-7 degrees C, dropping hydrochloric acid aqueous solution, washing with water, concentrating, separating, centrifuging to obtain dehydroepiandrosterone acetate; and (iii) performing hydrolysis reaction by adding crude product of dehydroepiandrosterone acetate, carbinol, potassium carbonate, hydrochloric acid, methanol and activated carbon in the ratio of 1:(7-8):(0.4-0.5):(0.3-0.4):(5-6):(0.4-0.5), refluxing dehydroepiandrosterone acetate, carbinol and potassium carbonate for 1.5 hours, cooling, adjusting the pH value to 6-8 by adding hydrochloric acid, adding activated carbon and refluxing for 30 minutes, filtering, concentrating, cooling to 0-5 degrees C, centrifuging and drying to obtain the dehydroepiandrosterone product.