The dynamic variation of ultraweak luminescence (UWL)and energy level, and their relationship under stress of 20% PEG treatment and drought stress with regulating of reactive oxygen by carrying out four treatments of PEG, PEG+hydrogen (H₂O₂), PEG+sodium benzoate and distilled water（CK）in Sedum hybridumseedling to supply theoretical basis for understanding the generation of UWL. The results showed: (1) in process of drought stress by PEG treatment, ATP content, energy charge and UWL intensity all decreased; above energy index and UWL intensity of PEG treatment decreased more rapidly and showed a bigger drop. (2) Under drought stress with regulating by H₂O₂ and sodium benzoate, ATP content, energy charge and UWL intensity of treatments of PEG+H₂O₂ and PEG+sodium benzoate all decreased along with stress time as well as PEG treatment; However, above energy index and UWL intensity of PEG+H₂O₂ were lower than those of PEG treatment, while above energy index and UWL intensity of PEG+ sodium benzoate were higher than those of PEG treatment. (3) Correlation analysis also showed that UWL intensity was positively correlated with ATP content and energy charge both under drought stress and under drought stress with regulation of reactive oxygen. Above results indicated: under drought stress and drought stress with regulation of reactive oxygen, energy level represented by ATP content decreased more rapidly than that of CK, UWL intensity decreased more rapidly than that of CK too; UWL intensity decreased along with the decline of ATP content. which indicated that the generation of UWL in plants positively related to ATP level.