Abstract: In the Western Songnen Plain irrigation area where intensive saline-alkali reed wetland located, the effects of butachlor to the ecological characteristics of the wetland reed and the enzymatic activity of the wetland soil were investigated. The results showed that butachlor reduced rapidly after a month when butachlor was apllied to the saline-alkali reed wetland at the concentration of 360, 710 and 1440μg/L. The data of the plant height, the stem diameter and the dry weight of the wetland reed were not significantly affected by the concentrations of butachlor. With regards to the physiology of the reed, when the concentration of butachlor increased, the decreasing trend of the photosynthetic rate, the stomatal conductance and the transpiration rate, and the increasing trend of the intercellular CO2 concentration were not significantly different between any treatments. However, the concentration of the soluble sugar decreased. The activities of the soil enzymes in the wetland were significantly different when the butachlor of different concentrations was applied. The activity of the soil catalase was especially inhibited at the medium and high concentrations. The activity of alkaline phosphatase in the wetland soil was not significantly affected. The activity of invertase was increased in the medium concentration, and it was not affected by the treatments under other concentrations. The results showed that after the treatment of butachlor(less than 1440μg/L), with regards to the wetland reed and the soil enzymatic activates, no significantly toxicological risk was detected.