In this study, we have investigated photo-induced changes of optical energy gap( $E_{OP)}$ and photoluminescence (PL) in amorphous ($alpha$-) S $e_{100-x}$G $e_{x}$ (x=5, 25 and 33) thin films prepared by conventional thermal evaporation method. In the $alpha$-S $e_{100-x}$G $e_{x}$ thin film, the $E_{OP}$ is obtained by a linear extrapolation of the ($alpha$hν)$^{frac{1}{2}}$ versus hν plot to the energy axis using the optical absorption coefficient ($alpha$) calculated from the extinction coefficient k measured in the wavelength range of 290~900nm. Although the values of $Delta$ $E_{OP}$ are very different, all films exhibit photo-induced photo-darkening (PD) effect that is a red shift of $E_{OP}$ . In particular, $Delta$ $E_{OP}$ in $alpha$-S $e_{75}$ G $e_{25}$ thin film exhibits the largest value (i, e., $Delta$ $E^{OP}$ ~40meV for $alpha$-S $e_{95}$ G $e_{5}$ , $Delta$ $E_{OP}$ ~200meV for $alpha$-S $e_{75}$ G $e_{25}$ , $Delta$ $E_{OP}$ ~130meV for $alpha$-S $e_{67}$ G $e_{33}$ ). PL spectra in $alpha$-SeGe by hν$_{HeCd}$ have no-Stokes shift (SS) and show a tendency dependent on both composition and illumination time. We explain the energy-induced phenomena such as the PD and thermal bleaching, the native charged-defect generation and the no-SS PL, etc..the PD and thermal bleaching, the native charged-defect generation and the no-SS PL, etc..tc..