The invention discloses an amide/imide structure polycarboxylate superplasticizer and a preparation method thereof. The amide/imide structure polycarboxylate superplasticizer is synthesized by amidation/imidization of amine-terminated polyether to obtain polymerizable polyether amine, and then copolymerization reaction with active monomers. The preparation method of the polycarboxylate superplasticizer provided by the invention has the advantages of simple and easily controllable technological operation, safe and environment-friendly synthetic process, low cost, energy saving and consumption reduction. Also the obtained amide/imide structure polycarboxylate superplasticizer has the advantages of high water-reducing rate, good flowing retention performance, long storage period, significantreduction of slurry viscosity under a low water-binder ratio and the like, thus solving the problems of great difficulty, difficultly available raw materials, many side reactions, harsh conditions, high cost and the like in the amide/imide polycarboxylate synthesis process.