A constructed wetland was built in southern Taiwan in 2007 for local stream water purification and ecosystem improvement. The inflow rate was approximately 1,350 m3/day. The wetland influents were mainly from the local streams containing secondary wastewater from hog farms located in the upper catchment of the wetland and drainage water from the farmlands. The influent water contained organic contaminants and nutrients, which needed to be removed. The mean measured hydraulic loading rate, hydraulic retention time, water depth, and total volume of wetland system were 0.1 m/day, 5.5 days, 0.7 m, and 7,800 m3, respectively. In this study, water, sediment, and plant samples were collected and analyzed quarterly for each wetland basin during the two-year investigation period. Results show that more than 77% of total coliforms (TC), 78% of biochemical oxygen demand (BOD), 88% of total nitrogen (TN), and 96% of ammonia nitrogen were removed via the constructed wetland system. Thus, the wetland system has a significant effect on water quality improvement and is able to remove most of the pollutants from the local stream through natural attenuation mechanisms. Results from the ecological investigation show that more than 50 different plant species and 45 different animal species were observed in the wetland system although this wetland had been created for less than four years. Except for stream water quality improvement and rehabilitating the natural ecosystem, this wetland also offered more water assessable eco-ponds and eco-gardens for public. This constructed wetland has become one of the most successful multi-function constructed wetlands in Taiwan.