The invention provides a preparation method of a catalyst for a technology of preparing propylene from methanol/dimethyl ether and the catalyst prepared by the method. The method comprises the following steps: (1) treating a ZSM-5 molecular sieve by using an alkaline solution, washing the ZSM-5 molecular sieve until neutral, carrying out ion exchange by using an ammonium solution to prepare a mesoporous ammonium-type ZSM-5 molecular sieve; (2) mixing a phosphorus-containing inorganic acid and a binder evenly to obtain a phosphorus-containing binder; (3) mixing the mesoporous ammonium-type ZSM-5 molecular sieve obtained in step (1), the phosphorus-containing binder obtained in step (2) evenly and molding to obtain a catalyst precursor; and (4) sequentially drying and roasting the catalyst precursor obtained in step (3) to obtain the catalyst. The preparation method is simple and easy to operate; the prepared catalyst is good in performance, high in hydrothermal stability and anti-coking ability, and long in service life.