A kind of new rare-earth half-metal LiPr2O4 is found based on the first-principle pseudo-potentials. The calculated and analysed electronic and magnetic properties include the spin-polarized energy band structures and the state densities, the charge distribution and the molecular magnetic moments of LiPr2O4. Then these properties are compared with those of Fe3O4. The electronic structures of Li-ions and Pr-ions and the mechanism of magnetic and electric properties of LiPr2O4 are both analyzed in system. From our calculation, LiPr2O4 is a kind of new II-A half-metal materials, which is different from II-B Fe3O4. The molecular magnetic moment 2.98 mu(B) of LiPr2O4 is lower than 4.0 mu(B) of Fe3O4. There are hybridized orbits near the Fermi level caused by strong crystal field. The molecular magnetic moment comes from Pr4f electrons that are up-spin. Hybridized orbits cause the charge distribution and spin-polarization of the new half-metal LiPr2O4. (C) 2008 Published by Elsevier B.V.