We present a first principles calculations of the second-order optical response functions as well as the dielectric function for ABO3 (A=K, Li, Ba; B=Ti, Ta, Nb) and A5B6C7 ( A=Sb; B=S, Se; C=I, Br ) ferroelectrics. Specially, we evaluate the dielectric function ( ) ( ) ( ) 1 2     i  and the second harmonic generation response coefficient  (2) (2, , , ) over a large frequency range. The electronic linear electro-optic susceptibility  (2) (, , , 0) is also evaluated below band gap. These results are based on the series of self-consistent LDA calculations within DFT.