Abstract: Effects of varying Pyrene levels in soil on the antioxidative activities and cytoplasm membrane permeability (CMP) in the rhizotaxy of rye grass were studied. The results showed that the effect of the Pyrene stress appeared mostly 20d after treatment. The contents of CMP, MDA and SS in the roots increased significantly under 100-400 mgkg-1 Pyrene addition in the soil. The membrane lipids of the rye grass roots showed serious peroxidation. On the other hand, the catalase(CAT) activity and non-enzymatic antioxidant GSH content added dramatically to protect the root cells from injuries. The activities of peroxidase (POD) and superoxide dismutase(SOD) reduced under the Pyrene stress, with the POD activity decreased significantly.