Apatite-type lanthanum silicates draw researchers. attention due to their good performance as electrolyte materials for IT-SOFC (intermediate temperature solid oxide fuel cells). In this paper we present Sr-doping effect on La10Si6O27 (LSO) via experimental method and ab-initio calculation: the samples were prepared through an optimized water-based sol-gel process. High purity, crystallinity compounds with and without Sr-doping LSO are obtained and the resulting materials were characterized by scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. Ionic conductivities and activation energies have been measured after sintering at 1500 °C and the effect of the Sr-doping has been investigated. The results show that the ionic conductivity is thermally activated and values lies between 4.5 x 10-2 and 1 x 10-6 Scm-1 at 873 K as a function of the Sr-doping ratio. The ab-initio calculation work shows the lattice parameter and band structure affected by Sr-doping, leading to the change of macro scope properties. The calculation results of activation energies were consistent with those obtained by experiments.