Landfill leachate usually contains high concentrations of pollutions that are seriously harmful to the environment and human health. The main purpose of this study was removing organic pollution, ammonia, nitrate and total nitrogen in Isfahan composting facility leachate by horizontal constructed wetland systems. A pilot-scale study was conducted on subsurface flow constructed wetland systems operated in horizontal mode (HFCWs).Two horizontal systems with different plants were constructed, one planted with Vetiver and the other one without plant as a control. They were operated identically at a flow rate of 27 l/day with a 5 day hydraulic retention time. The average removal efficiencies for control and experiment were BOD5, 9% and 30%; COD, 19 and 34%; TN, 37 and 50%; Ammonium, 8 and 26%; nitrate 33 and 40% respectively. Due to high concentration of pollutants (the mean leachate concentrations of COD, BOD5, TSS, NH4+ -N, NO3- -N, TN were 104514.9, 69200.0, 8478.3, 317.5, 4633.2 and 1500 mg/L, respectively) the subsurface flow constructed wetland systems with Vetiver plant is a suitable solution for leachate treatment.