Utilizing Maker fringe (MF) method, second-harmonic generation (SHG) has been observed within the GeS2–Ga2S3–CdS pseudo-ternary glasses through thermal/electrical poling technique. The SHG phenomenon was considered to be the result of breakage of the glassy macroscopic isotropy originated from the reorientations of dipoles during the thermal/electrical poling process. Under the same poling condition conducted with 5 kV and 280 °C for 30 min, the maximum value of second-order nonlinear susceptibility χ(2) of the poled (100−x)GeS2·x(0.5Ga2S3·0.5CdS) glasses was obtained to be ≈4.36 pm/V when the value of x is equal to 30. Nonlinear dependence of χ(2) on compositions of these glasses can be well explained according to the theory related to the reorientation of dipoles.