Take the nominally anhydrous jadeite mineral in jadeitite as research objects, useing FTIR with normal temperature and heterotherm, to analyse representation of structure water and thermal variation behavior of jadeite. The result shows: Representation of FTIR of M—OH stretching vibration concentrates mainly on four areas, 3 700～3 600, 3 570～3 520, 3 500～3 300 and 3 230～3 140 cm-1, but with different characterization in different jadeite. In the process of varying temperature, the relative absorption intensity of absorption band in 500 ℃ decreased obviously, and the content of structure water gradually decreased, further characterization of the “water” in jadeite minerals is in the form of structure water. But the absorption spectrum caused by M—OH stretching vibration, the content of structure water and fingerprint spectra near 850 ℃ changesobviously, indicating that the temperature of jadeite mineral composition has mutated. The thermal variation behavior of “water” in jadeite mineral provides some evidence in order to further understand the occurrence state and binding mode of water and diagenetic mechanism.