Electronic structures and chemical bonding were investigated on Bi4Ti3O12 substituted with lanthanides, such as La, Ce, Pr, and Nd for Bi, using the discrete variational X alpha method. Also, we investigated the effect of substitution atom on net charge and overlap population, which is related to the dielectric constant. We found that the net charge and overlap population were dependent on the substitution atom. We concluded that dielectric constant increases as the atomic number of substitution atom increases.