Abstract:The vigour of peanut seeds conditioned with 20% PEG at 10–15℃ for 8 hours was raised. The activity of catalase in 8 hours was higher than that in control. But the amounts of peroxides were lower than that in control. The activities of catalase and superoxide dismutase (SOD) in seeds treated with PEG were higher than that in control after germination for 3 days. The vigour index of seeds and fresh and dry weight of the 21 days seedling were increased. Mitochondria of cotyledons of peanut seeds at germination for 3 days were detached. Activities of acid phosphatase and DNase of mitochondria fraction were declined with the effect of PEG. But supernatant fraction did not change. Conductivity of peanut seeds treated with PEG was declined Therefore, structure of membrane was renovated with the effect of PEG.