Four samples of aeschynites have been studied, including one Ce-aeschysite, two Nd-aeschynite, and one Y-aeschynite, of which the first three were collected from the Bayan Obo iron and REE deposit in Inner Mongolia and the last from Xihuashan granite in Jiangxi.The present paper deals with characteristics of differential thermal curves of four metamict aeschynite samples and X-ray powder diffraction data of these samples at different temperatures, together with a discussion on linear relations between ThO2 and TiO2, ThO2 and Nb2O5, Ce203 and Nd203, and TiO2 and Nb2O5. From the study it is known that the four metamict aeschynite samples have the following characteristics:(1)so far as differential thermal curves are concerned, there is no exothermal peak at 700-800℃ for aeschynites which suffered no metamictization, but metamict aeschynites do have such a peak, and the higher the metamictization degree, the steeper the peak;(2)the deeper the metamictization, the higher the temperature of heating treatment required for restoring crystal form of the mineral] however, the temperature should not exceed 1200℃，(3)the higher the contents of radioactive elements thorium and uranium in aeschynites, the deeper the metamictization, e.g., No.1 sample (ThO2 5.79%)has suffered higher degree of metamictization than No.2 sample ( ThO2 1.28%)，(4)the metamictization degree of aeschynites is related to the variety of thorium and uranium; the Main No.1 (Th02 5.79%)sample, for example, has suffered higher degree of metamictization than Y-aeschynite which contains 10.08% U203.