The invention discloses a fluidized bed catalyst and a preparation method thereof. The preparation method comprises the following steps: evenly mixing adhesive and water; adding molecular sieves, homogenizing by mixing, adding a base material, and evenly stirring to obtain a suspension; regulating the pH value of the suspension, so that the suspension becomes gelatinous; drying the gel by a spray granulation method, thereby obtaining solid microspheres; roasting the solid microspheres; and carrying out acid treatment on the roasted solid microspheres, drying and roasting to obtain a fluidized bed catalyst. The catalyst prepared by the method disclosed by the invention has high abrasive resistance, and the abrasion index is lower than 2.0; and the invention solves the problem of poor abrasive resistance of the preformed catalyst product when independently using silicasol or other siliceous compounds as the adhesive. The low carbon olefin selectivity of the fluidized bed catalyst disclosed by the invention is very close to that of the corresponding molecular sieves; and thus, the fluidized bed catalyst is very suitable for the industrial production process of preparing low carbon olefins from methanol/dimethyl ether.