Abstract: This paper reported the changes of cell membrane permeability, process of cell physiological metabolism and some macromolecules and enzymes.The determined results of conductance and K⁺ consistency of leaky solution from leaves indicated that great quantity of electrolyte in leaf cells had leaked and the membrane permeability had dramatically increased under 0℃. When electrolyte greatly leaked, serious injury symptoms had occured outside of plants.After treatment with low temperature, the content of soluble sugar and free proline accumulated in leaf cells of Eichhorina crassipes as the protective matter of the chilling injury, but no obvious changes were determined about soluble protein content.The peroxidase activity decreased and its isoenzme electrophoretograms increased 1—4 bands, CAT activity inereased clearly and its isoenzyme electrophoretograms increased 1—2 bands, and SOD activity decreased slightly and its isoenzyme electrophoretograms increased 1 band after treatment under 0℃ for 36 hours. The dehydrogenase activity in plant roots decreased.