Lanthanum silicate La10Si6O27 nanopowders are synthesized via co-precipitation process. After the calcination at 900 degrees C and then removal of La2O3 by acid-washing, pure stoichiometric La10Si6O27 nanopowders are obtained, and are characterized by XRD, BET, TEM and ICP, respectively. The oxy-apatite ceramic with the density higher than 95% can be obtained at rather low sintering temperature of 1300 degrees C, which has comparable total conductivity with the samples sintered at 1650 degrees C from the powders prepared by solid-state reaction. Additionally, effects of sintering temperatures on electrical properties are also investigated in detail. It is found, that with the increasing sintering temperature from 1300 degrees C to 1650 degrees C, the grain conductivity monotonously increases; while the grain boundary conductivity increases first and then decreases with the maximum value at 1600 degrees C. The related mechanism is also discussed. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.