Five kinds of lithium rare earth tetraphosphate crystals (LiLnP4O12, where Ln represents Ce, Pr, Eu, Ho or Br) have been synthesized using high temperature flux method. Their physical and spectral properties have been investigated systematically. The study of the absorption and the fluorescence spectra of LiPrP4O12 shows that this crystal may be used as a promising laser material in the visible region.