The quality of seawater in Porphyra yezoensis culturing area in the Jiaozhou Bay wetland was surveyed and studied. Experimental study on the uptake effectiveness of nutritional elements such as nitrogen and phosphorous by P. yezoensis was carried out．According to the surveyed and experimental results，the bioremediation effects of P. yezoensis on eutrophic seawater was analyzed comprehensively．The results showed that there was an obvious reducing effect on the residual nutriments in seawater of the Jiaozhou Bay wetland by cultivating P. yezoensis.The contents of nitrogen，phosphorous and organic carbon as well as eutrophication index(EI) in culturing area were all lower than those in the control area．Under experimental conditions, P. yezoensis showed significant effectiveness on the uptake of nitrogen and phosphorous as well as reduction of eutrophication level．The decrease of content of dissolved inorganic nitrogen(DIN) was 17.15%-21.26% at the various experimental cycles and that of dissolved inorganic phosphorous(DIP) was 55.73%-61.12%，indicating that the uptake amount of DIP by P. yezoensis leafy thalli growth was obviously higher than that of DIN．In addition，the eutrophication level of water decreased from medium eutrophic with EI of 2.211-2.592 to oligotrophic with EI of 0.749-0.873 and the decrease rate of EI was 63.32%-69.39%．According to the natural environmental conditions of Jiaozhou Bay wetland,by cultivating seaweeds on a large-scale，the nutritional elements such as nitrogen，phosphorous and carbon can be removed in quantity and meanwhile the eutrophication level of seawater can be reduced efficiently．