The invention discloses a molecular sieve catalyst and a preparation method thereof, and the method comprises the following steps: (1) spraying water onto a molecular sieve carrier to atomize and pre wet the molecular sieve carrier; and (2) leaching the atomized and pre wetted molecular sieve carrier with a an aqueous solution containing an active component to load the active component onto the molecular sieve carrier. The molecular sieve catalyst with molecular sieve content up to 95 wt% is prepared successfully, the particle diameter of the molecular sieve catalyst is 0.3 mm to 2 mm, the specific surface area is 580-640 square meters per gram, pore volume is 0.35-0.4 ml / g, and the most probable aperture is 8-12 nanometers; and the prepared molecular sieve catalyst has high strength (30-50N / grain or 20N / mm) and high yield (97-98%), the preparation method is simple, drying sieving and once-more pre wetting are not needed, the process is more simple, broken ratio of the molecular sieve catalyst is reduced, and the yield is increased.