A zeolite composite with Beta and Mordenite zeolite structures (denoted as BMZ) was synthesized with a two-step hydrothermal crystallization process, and characterized by X-ray diffraction, scanning electron microscopy, N-2 adsorption, NH3-TPD and in situ IR spectra of pyridine. The results show that the composite has microprous and mesoporous structures and distinguished acid properties, the acid amount and concentration ratio of Lewis to Bronsted-acid sites in the composites can be controlled by changing the alkalinity in the second-step synthesis. Over the composite catalyst H-BMZ, the conversion of methanol in the mild condition reached 90% and the selectivity of dimethyl ether almost kept 100%.