The present invention provides a method for preparing an amide. The method includes the steps of performing in a reactor including a catalyst composition having a nitrogen-containing heterocyclic compound and sulfuric acid Beckman rearrangement of a ketoxime to form a product stream having the amide, wherein a molar ratio of the nitrogen-containing heterocyclic compound to the sulfuric acid is from 1:1 to 1:8; and separating an organic phase having the amide and an aqueous phase having the catalyst composition from the product stream. The present invention facilitates the regeneration of the catalyst composition with low water content, so as to increase the conversion rate of a ketoxime and the selectivity of an amide.