The Al-27 MAS/NMR spectra of La4/3-yLi3yTi2-xAl4x/3O6 (y=0.21, x=0.01-0.60) were studied by the Massiot fitting program. The result shows a single signal Q1 produced by the second-order quadrupole interaction in low concentrations of x=0.01-0.28. But in the high concentrations of x=0.30-0.60, there are two components Q1 and a small and narrow component Q2 obtained. The quadrupole interaction parameters eta(Q) and nu(Q) were estimated. We firstly found that the quadrupole interaction parameters eta(Q) and nu(Q) were correlated with La3+ occupation, lattice parameters and Al3+ Position and affected the ionic conductivity in the materials. (c) 2005 Elsevier B.V. All rights reserved.