The invention discloses a p-xylene fluid catalyst prepared by performing alkylation of methylbenzene methyl alcohol and a preparation method of the p-xylene fluid catalyst. The p-xylene fluid catalyst is prepared by modeling mixed spray of ZSM-5, matrix and amorphous binding agent, modifying by alkaline-earth metals, non-metals or/and rare earth metals and modifying by a siloxy group compound to prepare corresponding catalysts. The catalyst is used in methylbenzene methyl alcohol alkylation reaction; based on full conversion of methanol, methylbenzene conversion rate is more than 20 percent, and the once through yield of p-xylene in the product is up to 25 percent.