Bismuth-doped LaAlO3 was prepared in the form of solid solution, La(1-x)BixAlO3 (0≤x≤0.2), by solid-state reactions. The materials were characterized by x-ray diffraction and dielectric spectroscopy. With increasing bismuth amount (x), the dielectric constant increases from 31.6 for pure LaAlO3 to 34.6 for x=0.2, while the loss tangent drops from 0.03 to 0.004 (f=100 Hz). The frequency dispersion of the dielectric constant is attenuated. The improved dielectric properties in the Bi-doped LaAlO3 are attributed to the high polarizability of Bi3+ ion with a lone electron pair.