The Raman spectra of lanthanum-doped intergrowt h ferroelectric ceramics Bi_4-xLa_xTi_3O_12-SrBi_4-yLayTi_4O_15［BLT-SBLT(x+y),x+y= 0.00, 0.25,0.50,0.75,1.00,1.25,1.50］achieved at room temperature were inve stiga ted. The results show that La was substituted the Bi ions in the pseudo-perovski te blocks when La content is lower than 0.50 When La content is higher than 0.50, so me of La ions are incorporated into the (Bi_2O_2)^2+ blocks. The inco rporation of La ions into the (Bi_2O_2)^2+ layers would change th e structure of (Bi_2O_2)^2+ and destroy its functions as the insu lating layers and the space charge storage, which leads to the decrease of the remnant polarization. The relaxation characteristics observed in BLT-SBLT(1.50) are consistent with the softening of the mode lower than 30 cm^-1. This in dicates that La-doping may bring about the structural phase transition.