The invention discloses a catalyst used for low carbon olefin preparation by means of oxygenated chemical transformation, and a preparation method thereof. A small crystal particle ZSM-5 molecular sieve with a particular shape can be obtained by adding low-concentration hexadecyl trimethyl ammonium bromide (CTAB) during the synthesis. The catalyst prepared in the invention is applicable to the process of the low carbon olefin preparation by means of oxygenated chemical transformation. Compared with the condition without the CTAB addition during the ZSM-5 molecular sieve preparation with the same method, the catalyst achieves higher low carbon olefin yield, especially propylene yield. Meanwhile, the preparation method of the catalyst is simple and suitable for industrial production.