La(0.57-2x/3)SrxLi0.3TiO3 perovskites were synthesised using a conventional solid-state reaction. Large Sr2+ ions partially substituting for La3+ ions were found to disturb the cubic perovskite structure and cause the superstructure lines to gradually decrease in the x-ray diffraction patterns and almost disappear when x = 0.12. On the contrast, there still exist superstructure diffraction spots in the electron diffraction pattern on microdomain when x = 0.12. The lithium ion conductivities of the compounds were improved in the range of 0 less than or equal to x less than or equal to 0.08, which does not obey the principle of the carrier concentration. An expansion of the unit cell and the disordering of La3+ (Sr2+), Li+ ions and vacancies in A sites could be a mechanism for the enhancement of the conductivity with Sr2+ doping.