The invention provides an aromatization auxiliary agent and a preparation method thereof, wherein the aromatization auxiliary agent comprises (calculated as the dry base) 15-60 wt% of natural minerals, 10-30 wt% of an inorganic oxide binder, and 20-80 wt% of a phosphorus-containing and loaded-metal-containing MFI structure molecular sieve. According to the present invention, with the application of the aromatization auxiliary agent in the hydrocarbon oil adsorption desulfurization reaction, under the premise of no reducing of the desulfurization activity of the main catalyst, the olefin content in the gasoline can be significantly reduced, the aromatic hydrocarbon content can be increased, and the octane number of the gasoline can be increased.