Abstract: Pot-cultured tobacco plants of 14 leaves were waterlogged for 2, 4 and 6 days respectively, the changes of superoxide dismutase (SOD)and other physiological parameters were determined.The results showed that with the extension of waterlogging time, the relative activity of SOD and the relative content of soluble sugar increased remarkably, but the relative content of malonaldehyde (MDA)was increased at first and decreased subsequently.The three indices (SOD,MDA and soluble sugar)did not reach the control's level after the treated plants rehabilitated in normal conditions for 2 days.