Abstract: Mesoporemicrospore composite molecular sieves were synthesized under hydrothermal conditions by use of cetyltrimethylammonium-bromide(CTMAB) and tetramethylammonium (TMAOH) as the templates. The as-synthesized composite molecular sieves showed diffraction peaks at small and large angle regions in their XRD patterns, which correspond to the mesopore and microspore structures. IR spectra showed that the as-synthesized sample had characteristic absorption bands of mesoporous MCM-41 and microporous ZSM-3 molecular sieves, and their IR spectra are clear different between composite molecular sieves and mechanical mixture. The N2 absorption and desorption isotherms of the as-synthesized samples showed that the sample was a composite molecular sieve, and the corresponding BJH pore size distribution of the material indicated that there were two kinds of pores mainly located at 0.7 nm and 3.3 nm. The SEM images of composite molecular sieves is different from the mechanical mixture's, the former is that the ZSM-3 overgrowth on MCM-41 or MCM-41 re-crystal, the latter is evenly scatter and not re-crystal images.