The present invention provides a method for preparing amides, in which an amino acid ionic liquid is used as both a reaction medium and a catalyst to catalyze Beckman rearrangement of a ketoxime, so as to produce an amide. In the method, the rearrangement is conducted by catalyzing a ketoxime with an amino acid ionic liquid having the asymmetric property at a moderate reaction temperature during a short reaction time, so as to produce an amide without adding other catalysts such as concentrate sulfuric acid. The method has advantages such as avoiding corrosion in equipments with pipelines, the high conversion rate of ketoximes and the high selectivity of amides.