The zeolite Beta is considered as a promising additive for FCC catalyst in diesel oil production. In this article, it is shown that hierarchical zeolite Beta obtained by an optimized desilication procedure increases diesel and propylene yields during gas-oil cracking reaction. The alkaline treatment of zeolite Beta (Si/Al = 22) by desilication with NaOH and NaOH&TBAOH was investigated. The catalytic performance improvement of desilicated zeolite Beta has been rationalized by deep characterization of the samples including X-ray diffraction, low-temperature adsorption of nitrogen, solid-state 29Si MAS NMR and IR studies of acidity. Finally, the catalytic performance of the zeolites Beta was evaluated in the cracking of n-decane, 1,3,5-tri-iso- propylbenzene, and vacuum gas oil. It was found that desilication with NaOH&TBAOH ensures the more uniform intracrystalline mesoporosity with the formation of narrower mesopores, while preserving full crystallinity resulting in catalysts with the most appropriated acidity and then with better catalytic performance.