Abstract: The objective of this experiment was to study changes of antioxidative enzymes and lipid peroxidation in root of wheat seedlings exposed to water stress, as affected by CO_2 laser (wavelength 10600 nm, power density 20.1 mW/mm~2) pretreatment, Wheat seed embryos were exposed to CO_2 laser radiation for 0,1,3 min and 5 min,respectively,and when the seed-lings were 12 days old they were treated with 10% (W/V) PEG6000 solution for 8 days. Chan-ges in the concentration of malondialdehyde (MDA) and hydrogen peroxide (H_2O_2), the pro-duction rate of superoxide radical (O_2~-) and superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) activities of root and the growth parameters of root (root length and root dry weight) were measured to test the effects of laser pretreatment. The results showed that suitable laser pretreatment of embryos had positive effect on the root of wheat seedlings subjected to water stress, such as decreasing the concentration of MDA and H_2O_2, the production rate of O_2~- and increasing the activities of SOD, POD, CAT and APX of root and root length and root dry weight. It was suggested that those changes in MDA, H_2O_2 and O_2~-,anti-oxidative enzymes of root and root growth and development were responsible for protection wheat against water induced oxidative damage.