The injuries of Lemna paucicostata L. due to linear alkylethoxylate (AE) were studied by means of several measurement indices:catalase (CAT) activity,peroxidase (POD),plant biomass increment and changes in pH. The results showed that the injury degree of Lemna paucicostata L. was directly responded to the concentrations of AE. When the concentration of AE was lower than 1.0 mg/L, Lemna paucicostata L. was injured slightly. With the increasing of CAT and POD activities,those peroxides on the membranes could be cleaned. When the concentration of AE was 10.0 mg/L, Lemna paucicostata L. was injure...