The invention discloses a catalyst for preparing dimethylbenzene by converting methanol. The catalyst disclosed by the invention consists of a ZSM-5/EU-1 composite molecular sieve and boron, wherein the ZSM-5/EU-1 composite molecular sieve is 95-99.5wt% of the weight of the catalyst; the weight ratio of a ZSM-5 molecular sieve to an EU-1 molecular sieve is 1:(0.1-10); and the loading amount of the boron is 0.05-5wt% by measuring according to the element. Due to the mutual synergistic effect of different types of molecular sieves and non-metallic elements, the catalyst disclosed by the invention has a higher activity; and meanwhile, the selectivity of a target product dimethylbenzene for the dimethylbenzene is greatly improved, so that the catalyst disclosed by the invention can be applied to a process of preparing dimethylbenzene by converting methanol and has the advantage of being high in methanol conversion rate and dimethylbenzene selectivity.