The dynamic variation of ultraweak luminescence (UWL) and its relationship with reactive oxygen were studied during the simulated drought stress with PEG6000 solution and?hydrogen peroxide (H₂O₂) treatment, and sodium benzoate treatment under the PEG simulated drought stress process in Sedum hybridum. The results showed that the superoxide anion radical（O₂^-）production rate, malondialdehyde (MDA) content and relative electric conductivity of the PEG treatment and CK in the drought stress process increased continually, while the UWL intensity decreased. Meanwhile, the O₂^- production rate, MDA content and relative electric conductivity of the PEG treatment were all higher than those of CK except that the UWL intensity was lower than that of CK in the whole drought stress process. During H₂O₂ treatment and sodium benzoate treatment under the PEG simulated drought stress process, the O₂^- production rate, MDA content and relative electric conductivity under PEG+H₂O₂ treatment, PEG+sodium benzoate treatment and PEG (CK) increased continually, while the UWL intensity decreased. In whole drought stress process, the O₂^- production rate, MDA content and relative electric conductivity under H₂O₂ treatment were all higher than those of CK, except that the UWL intensity was lower than that of CK. However, the O₂^- production rate, MDA content and relative electric conductivity under benzoate treatment were all lower than those of CK, except that the UWL intensity was higher than that of CK. During the PEG simulated drought stress with H₂O₂ treatment and sodium benzoate treatment under the simulated drought