Alkali metal chlorides have significant effects on the crystallization and characteristics of MNaZSM-48 (M=Li, Na, jK, Rb, Cs) zeolites. XRD patterns showed that introduction of different alkali metal chlorides does not strongly affects the structures of the products, but it greatly slows down zeolites crystallization rates. The as-synthesized samples are also characterized by SEM, TG/DTA, XPS and plasma spectra. It was shown that the crystal morphologies and sizes, and the thermal properties depend on the kinds of alkali metal chlorides. KNaZSM-48 and RbNaZSM-48 are not stable, and easily transform into alpha-SiO2 through calcination. The SiO2/Al2O3 ratios in the bulk of MNaZSM-48 are basically the same, but the SiO2/Al2O3 ratios on the surface are strongly different. The catalytic measurement showed that KNaZSM-48, RbNaZSM-48 and CsNaZSM-48, used as supports of catalysts, respectively, possess better catalytic properties in the CO hydrogenation to light olefins.