According to chemical composition, exchangeable cation and thermal behaviors of crystal structure, Xuancheng zeolite should belong to calcium-rich clinoptilolite with low thermal stability. Optimal test conditions were determinedby orthogonal experiments, and then CEC values were measured under such conditions. The results show that when the roasting temperature is lower than 400℃, only an indistinctive change in CEC value of the clinoptilolite occurs, whereas at 250℃, the CEC value slightly rises and reaches its maximum. This is ascribed to the calculation basis discrepancy caused by the decrease of volume density. Between 250℃ and 400℃, the CEC value of Xuancheng zeolite decreases slowly. When the baking temperature exceeds 400℃, the CEC value drops sharply. Thermaland X-ray diffraction analysis has proved that there exists a starting point of 250℃ in structure destroy and an abrupt change at 400℃, which causes rapid decrease in CEC value at a high temperature. It is thus concluded that when calcium-rich clinoptilolite is used as an ion exchange reagent, the processing temperature should not exceed 400℃. 