Abstract: With alkali-treated beta zeolite as the sources of silicon and aluminum and cetyltrimethylammonium bromide (CTAB) as template, mesoporous aluminosilicates with hexagonal structure denoted as B-MCM-41 were synthesized. The structure and acidity of B-MCM-41 were characterized by XRD, N₂ adsorption-desorption, FT-IR, ²7Al MAS NMR, HRTEM and NH₃-TPD. Compared with conventional mesoporous aluminosilicates materials, B-MCM-41 synthesized in this way exhibits enhanced acidity and higher activity for catalytic dealkylation of C⁺₁0 aromatic hydrocarbon. B-MCM-41 mesoporous structure may be built in the presence of a cationic surfactant template via the assembly of the dissolved fragments such as five member secondary structural units which are formed from the dissolution of preformed beta zeolite in a caustic solution.