Abstract: This article describes the synthesis and characterization of a novel MCM-41/ZSM-5 composite molecular sieve. The composite was synthesized under hydrothermal conditions by use of cetyltrimethylammonium bromide as the template and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), infrared spectroscopy and N₂-sdsorption, respectively. The results indicated that the sample was a composite molecular sieve which was different from ZSM-5 zeolite and MCM-41 sieve. The influence of the synthesis parameters was discussed. It was shown that the gelation time, aged temperature and the quantity of CTAB played an important role in the synthesis.