The invention discloses an ultrasound-assisted preparation method of N-(quinoline-2-yl) alkyl amide. Under ultrasound assistance and catalysis of sulfonic acid cationic exchange resin, C2-N-amidationis performed on quinolone N-oxide, so as to obtain N-(quinoline-2-yl) alkyl amide. The method uses raw materials easy to obtain, is performed under simple, mild reaction conditions, is environmentallyfriendly and energy-saving, and has high reaction selectivity and yield; substrate functional groups are highly compatible; particularly, the sulfonic acid cationic exchange resin is used as an acidcatalyst, is easy to recycle and reuse, lowers reaction costs, and solves the pollution problem of traditional proton acid catalysis reaction, thereby having higher application value.