Triphylite-lithiophilite, a perfect isomorphous series, has been found in six mineral occurrences of China, Of these, four are in the rare-metal granite pegma- tite$ of Xinjiang where all of the samples are lithiophilite, The Mn-rich features are also observed in other Fe, Mn minerals of Xinjiang pegmatites. In 1984, a few specimens of triphylite were discovered in Napping rare-metal pegmatite of Fujian. The mineral is one of the few Fe, Mg-richest triphylites in the world, Another triphylite occurs in Shangxian pegmatite of Shanxi province, L1p to pow, a pe- rfect triphylite-lithiophilite series has been foupd ip Chipa, whose mineralogical properties are all listed in the paper. Researches on the chemical compositiop of triphylite-lithiophilite show that, besides the major constituents Fe2+ and Mn2+，the cations at the octahedral M ( 2 ) site in the minerals are Mg2+, Ca2+, Fe2+.The highest Mg0 content is 7.38 wt%. Geperally speaking, Mg2+ replaces Fe2+ easily, while Ca2+ sometimes substitues for Mn2+ at the M ( 2 ) site, Pure triphylite has not been found yet in the nature and LiFe[P04] contents of all native triphylites are lower than 80%.Neverthe- less, there are very pure lithiophilites in nature. The paper illustrates the relations of chemical composition (Fe/Mn) to physical properties, optical properties and unit cell dimensions of the series, With the increase in Fe/Mn ratio, the specific gravity and the index of refraction will grow up, the cell parameters will decrease, and the optic axial angle will vary regularly, The rising of Mg2+, Ca2+ contents of the minerals, on the other hand, will also cause an obvious variation in the above properties. The IR spectral analysis of four triphylite-lithiophilite samples collected in China has been made to find the correlation between chemical composition and IR absorb peaks, The results show that there exists gocd linear correlation bet- weep absorb peaks from 475-455cm-1 and chemical composition; it 'is therefore feasible to use IR spectra for semi-quaptitative determination of chemical compo- sition of this series.