To investigate the removal of pesticides by wetland, organic pesticide nicosulfuron was selected as the test substance. Removal of nicosulfuron was investigated using horizontal subsurface constructed wetland and vertical subsurface constructed wetland under different hydraulic load conditions. The roles of plants and media in the constructed wetlands in the removal of nicosulfuron were also studied. The experimental results indicate that with the increase of hydraulic load, the removal rate of nicosulfuron in both constructed wetlands decreases. Under the same conditions, the removal of nicosulfuron by horizontal subsurface constructed wetland is better than that by vertical subsurface constructed wetland. Plants in both wetlands can uptake nicosulfuron, and roots act important role. Calamus can tolerate nicosulfuron better than softstem bulrush. The media in the wetlands can adsorb nicosulfuron, and the adsorption capacity of zeolite and gravel are greater than that of steel slag.