The scientific significance of research of trace water in nominally anhydrous mantle minerals is described; the research progress in this field are reviewed, including the following seven aspects:(1)confirmation of structural water, (2)determination of the amount of water, (3)incorporation mechanism of hydrogen, (4)the structural site of hydrogen, (5)stability of hydrogen, (6)solubility of hydrogen, and (7)hydrogen isotope compositions of some nominally anhydrous minerals; some problems and difficulties are pointed out, such as (1)the investigations of natural samples are not so enough, (2)the calibrations of IR for some minerals haven' t been made, (3)we know very little about the incorporation mechanism and structural site of hydrogen, (4)there is only a little information for stability and solubility of hydrogen,and (5)hydrogen isotope compositions of nominally anhydrous minerals are scarce; the future research emphases of this field are suggested.