CXN zeolite, a natural STI type zeolite in China, was modified by ion exchange and calcination. The structural properties of raw zeolite and modified zeolite were characterized by chemical analysis, powder XRD, TG/DTA, ^2^7Al MAS NMR, ^2^9Si MAS NMR and nitrogen adsorption. The raw zeolite is rich in calcinium with cell composition of Na~0~.~2Mg~0~.~1Ca~8~.~4[Al~1~7~.~2Si~5~4~.~8O~1~4~4]. 65H~2O. After treatment of ion-exchange and de-calcinium, the zeolite was found to be de-alunminumated in the framework during calcination. Therefore the thermal stability of the modified zeolite was increased from 500℃ for raw material to 700℃. The type I adsorption isotherm of nitrogen proved the nature of the micropore in the zeolite.

Key words: ZEOLITE, ION EXCHANGING, THERMAL STABILITY, X-RAY DIFFRACTION ANALYSIS, THERMOGRAVIMETRY, NITROGEN, ADSORPTION