Abstract: Investigating the toxic effects of ionic liquids on crops could provide basis for the effects of ionic liquid on ecological environment. Effects of 1\|hexyl\|3\|methyl imidazolium bromide ionic liquid（1\|hexyl\|3\|methyl imidazolium bromide， ［C6mim］Br）on the growth， physiological and biochemical characteristics of maize seedlings（Tunyu 118） were evaluated by hydroponics with different concentrations of ［C6mim］Br（0， 5， 10， 15 mg·L-1）. The results showed that when ［C6mim］Br concentration was greater than or equals to 10 mg·L-1， plant height and root length of maize seedling were decreased significantly（P<005）， and the content of soluble sugar in the leaves was decreased significantly（P<001）. Compared with the normal control， the contents of soluble protein in the leaves was decreased significantly whatever ［C6mim］Br concentration was set in this study. The POD activities were significantly lower than that of the control when ［C6mim］Br concentration was greater than or equals to 10 mg·L-1. When ［C6mim］Br concentration was≥15 mg·L-1， the reducing of superoxide dismutase（SOD） activity and increasing of superoxide anion（O·-2） rate all reached significant level（P<001） compared with the control. It proved that ionic liquid ［C6mim］Br was harmful to maize， and with the increase of ionic liquid concentration， the poison increased.

Key words: ionic liquid, maize, poison, soluble protein, SOD, POD