The invention provides a method for preparing amide. The method includes weighing triphenyl phosphine oxide, oxalyl chloride, organic acid and organic amine according to a molar ratio of 1-5:1-5:1:0.3-4; adding the triphenyl phosphine oxide, the oxalyl chloride, the organic acid and the organic amine into a reaction vessel, stirring the triphenyl phosphine oxide, the oxalyl chloride, the organic acid and the organic amine in N2 environments and carrying out reaction on the organic acid and the organic amine in the presence of organic solvents at the reaction temperature of 10-40 DEG C for the reaction time of 0.5-5 hours to generate the corresponding amide. The method has the advantages that the triphenyl phosphine oxide is used as a novel carboxylic acid activating agent to promote synthesis of the amide, the method is low in reaction temperature and short in reaction time, and the triphenyl phosphine oxide which is the carboxylic acid activating agent is inexpensive, is easily available and can be recycled; only reaction byproducts CO and CO2 can be generated, and accordingly the method is high in atom utilization rate.