The existence of optical nonlinear properties in silver-oxide-doped and -undoped germanotellurite glasses by using thermal poling treatment was demonstrated and compared. The variation of second-order nonlinear optical characteristics with poling voltage and their stability with time were observed via the macroscopic second harmonic generation measurement. The study also includes the investigation of enhancement of the nonlinear property by thermally poling K[Nb 1/3 Te 2/3 ] 2 O 4.8 volume-distributed glass-ceramic composite in which the role of silver in ceramic component and the modified surface structure layer of the glass component would be further discussed.