34 pyrope samples from the Liaoning No. 50 diamondiferous kimberlitepipe and the Kuandian alkali basalt in Liaoning Province were carefully analyzed by using infrared spectroscopy and electron microprobe. It has been found that some coarse pyrope crystals from kimberlite have constitutional water, Whose content is uniform in a grain but varies remarkably from grain to grain: the estimated content is about 0.07 % in a comparatively water-rich sample, whereas no constitutional water has been found in six pyrope samples from alkali basalt. Two kinds of spectra were recorded, i. e.three-peak band and one-peak band, in which the frequency of The band near 3570 cm-1 is obviously controlled by Mg2+ and Fe2+ in octahedral coordina-tion but has little to do with six-coordinated Cr3+ and Al3+. The model(H4O4)4- =(SiO4)4- in pyrope lattice is still problematic in interpreting all the experimental xesults: in addition to(H4O4)4-, other substitute forms axealso likely to exist.