A kind of Si-Al composite zeolite was synthesized by hydrothermal method and characterized by XRD, nitrogen adsorption-desorption and IR. The results of XRD show that the zeolite belongs to hexagonal symmetry, and it is a pure phase. The composited zeolite possesses both microporous and mesoporous structures base on the pore size distributions, and presents much more Bronsted and Lewis acidic sites than HZSM-5. The catalytic cracking activity of 1,3,5-triisopropylbenzene over the hierarchical zeolite is more than that over HZSM-5 due to its mesopore structure and more acid amount.