The photoluminescence spectra and optical absorption spectra were measured for GD a-Si :H films prepared at different substrate temperatures. It is found that increasing bonded hydrogen centent results in a systematic increase of the photoluminescence peak intensity, peak energy, linewidth, Stokes shift, and thermal quenching. From the experimental results we infer that: (1) The bonded hydrogen may generate radiative recombination centers as well as may remove non-radiative recombination centers; (2) The increase of the bonded hydrogen centent results in increase of the elec-tron-phonon interaction and a slight reduction in the band tail width.