The pink opal is a mineral aggregation of opal and palygorskite. The minerals composition and spectral characteristics of the opal have a significant difference with the traditional opal of play of color. The thermal variation behaviors of the pink opal are studied by means of differential thermal analysis and Fourier transform infrared spectroscopy (FTIR) under room temperature or variable temperature. The results show that the infrared absorption band of the pink opal characterizes the vibrational characteristics of silicate minerals palygorskite and silico oxide opal. The infrared absorption band caused by the structural water expansion vibration is mainly characterized by a group of infrared absorption bands with different intensities in the range of 4000-3000 cm -1. The infrared absorption band caused by sum frequency and frequency doubling of vibration frequency of structural water, crystalline water and adsorptive water is mainly concentrated in the range of 8000-4000 cm -1. With the increase of temperature, the relative absorption intensity of the absorption band is decreasing, and the absorption peaks also have different degrees of drift, splitting or addition. It shows that the binding of —OH has no relation to Si 4+, and is related to Mg 2+, Al 3+, Fe 2+ and Fe 3+ in palygorskite.