The invention relates to the chemical field, in particular to a deep hydrodesulfurization solid-acid catalyst of gasoline and a preparation method thereof. Keggin-structure polyoxometallate (POM) is carried on a nano-sized ZSM-5 molecular sieve, and nickel nitrate is added to improve the catalytic performance of the catalyst. The invention is applicable to the modification of gasolines such as FCC gasoline, DCC gasoline, thermal cracking gasoline, coker gasoline and the like. The sulphur content in the gasoline treated by the catalyst is greatly reduced, and the catalyst has good low-temperature aromatization performance and is an ideal desulfurating, olefin-reducing and low-temperature aromatization catalyst.