The method for preparing acetaminophen relates to a technological process for making hydrogenation reduction of p-nitrophenol and acetylation reaction of p-aminophenol in same process and adopting acetic acid and acid anhydride to make combined acidation. Said invention is characterized by that in medium acetic acid/acetic acid aqueous solution, under the action of catalyst the p-nitrophenol can be reduced into p-aminophenol by means of catalytic hydrogenation, then the catalyst is filtered from reduction product, said product can be acidated by using acetic acid in the medium at 100-150 deg.C, the conversion rate of p-aminophenol is 30-80%, then the excess acetic anhydride can be added at 50-100 deg.c to make p-aminophenol completely acidate, then the above-mentioned is separated and refined so as to obtain the acetaminophen finished product. |