Abstract: The large constructed wetland engineering applied to the tributaries of the estuary is a new attempt in China, which may control the pollutant in tributaries and reduce the polluted load of the main stream. This research investigated the spatio-temporal characteristics of various chemical speciation of nitrogen in typical estuary of the Liaohe River Reserve. Based on the sampling work conducted in April to July of 2012,the spatio-temporal distribution characteristics of various nitrogen in the surface water and porewater of Qixing wetland were analyzed. The results showed that the NH₃-N concentration was higher in pore water than in surface water. In contrast, the NO₃-N and NO₂-N concentrations were higher in surface water. The pollutants decreased through the wetland to outlet. NH₃-N concentrations showed decreased trend over time, and the NO₃-N and NO₂-N concentrations were fluctuated. The Qixing wetlands can remove total of 2.05 t of NH₃-N in the half year.