Abstract: ZSM-5 was insitu synthesized on silica gel by using nbutylamine as the template and characterized by XRD, SEM, FTIR and N2 adsorption. The results indicated that the synthesized sample not only has a composite structure with ZSM-5 and silica gel, but retains the shape of silica gel microsphere. To obtain detailed information on the rules of synthesized chemistry, the effects of SiO2/Al2O3 of initial gel, H2O/SiO2, BuNH2/SiO2, OH-/SiO2, crystallization time and crystallization temperature on ZSM-5 crystallinity were systematically studied. The composite materials were tested in a micro fixedbed reactor, using Daqing Vacuum Gasoline Oil (VGO) as the feedstock. The results showed indicated that the composite structure zeolite yields more light olefins and has good selectivity to light olefins.