The South Lake Taihu region is increasingly threatened by water eutrophication, so it is important to understand phosphorus status in sediments and water of the riparian wetlands in this region and develop sound technologies for optimizing wetlands'ecological values. 29 typical sampling sites in this region were chosen for the investigation, and the sites located at Hangzhou West Lake, Deqing Xiazhuohu Wetland, and Changxing Baoyanghe River were selected for static column simulation experiments and steady-flow flume simulation experiments. According to the investigation, total phosphorus (TP) and NaHCO₃ (pH=8.5) extractable phosphorus (Olsen-P) in sediments of the region reached 0.169-1.200g/kg and 7.08-67.08mg/kg, respecially, and the adsorption capacity (Q_max) of sediments varied from 269.5 to 824.5mg/kg. NaOH+EDTA extractable phosphorus (NaOH+EDTA-P) constituted 52.0%±11.6% of TP, while Olsen-P was increased as organic phosphorus accumulated. TP in overlying water was 0.036-0.944mg/L, while dissolved reactive phosphorus (DRP) was relatively and 34.5% of the total sites was below detective limits. Total particle phosphorus (TPP) contributed 70.9%±13.2% of TP in water samples. There was no significant relationship between TP, DRP in overlying water and TP, NaOH+EDTA-P, Olsen-P in sediments, implying that phosphorus status in sediments was not the only factor restricting phosphorus in overlying water. In the static column simulation experiments, DRP in overlying water decreased slowly at the beginning, then decreased fastly later on. A quasi U-pattern curve was found in the steady-flow flume simulation experiments, i.e. DRP in the overlying water decreased at first and then turned to be increasing. It indicated that the role of the sediments might be changed from phosphorus "sink" to "source" when high phosphorus water flow over a wetland in rain season. It was also proved in the simulation experiments that organic matter accelerated the adsorption rates of phosphorus by sediments.