The invention discloses a method for preparing the silicoaluminate form of the AEI zeolite structure with high yields, and application in catalysis of the method. The present invention relates to a new process for synthesising the silicoaluminate form of the AEI zeolite structure based on the use of another zeolite, zeolite Y, as the only source of silicon and aluminum, in order to obtain high synthesis yields (greater than 80%) in the absence of any other source of silicon, phosphine-derivedcationsand fluoride anions in the synthesis medium. The N, N-dimethyl-3,5-dimethylpiperidinium cation may be used as the OSDA, and the FAU crystal structure is transformed into the AEI crystal structure with high yields. It also discloses the preparation of catalysts based on the silicoaluminateform ofthe AEI crystal structure, wherein Cu atoms have been introduced, and the subsequent application thereof as a catalyst, preferably in the SCR of NOx.