Abstract: This paper studied the content malodialdehyde (MDA), the leakage rate of electrolyte in leaves of various rice va rieties with different iron toxicity tolerance, of Echinochloa crusgalli under excessive Fe²⁺(160mg稬^-1) stress.The results showed that both the MDA content, the leakage rate of electrolyte in leaves of plants were significantly, negatively correlated with the tolerance of test plants to iron toxicity.It was suggested that both MDA content, leakage rate of electrolyte could be used as the index for evaluating the tolerance to iron toxicity.