A catalyst containing an MWW-structured molecular sieve is characterized in that a nitrogen adsorption-desorption BJH curve of the MWW-structured molecular sieve shows that the nitrogen desorption capacity is 0.01-0.15cm<3>/g at 3.8+/-0.5 nm. Compared with a conventional hydrothermally synthesized catalyst, the catalyst provided by the invention can remarkably increase the conversion rate of ethylene while maintaining high ethylbenzene selectivity; compared with a BEA molecular sieve catalysts widely and industrially applied at present, the catalyst provided by the invention has better ethylbenzene selectivity.