Photoluminescence from Si/Si1-xGex/Si under [110] uniaxial tensile stress was investigated at 4.2 K. The photoluminescence intensity shows a minimum value at a certain strain field (epsilon(min)), which shifts to a higher strain field with increasing alloy composition (x). On the other hand, the deformation potentials obtained from the peak shift of Si1-xGex under stress are consistent with the calculation assuming that the built-in sh-ain in the Si1-xGex is coherent. These results indicate that the local symmetry in the Si1-xGex layer plays an important role on the light emissivity.