The enclosures with different food chains were seted in Baiyangdian lake in order to control eutrophication.From August 2010 to october water samples in Baiyangdian like were collected once a week,eight times together.Through measuring the concentration of pH,DO,SD,CODMn,TN,NH+4-N,TP and chlorophyll-a,the paper researched the effect of enclosure ecological system to water quality.The result shows that the water quality turned better obviously and the level of eutrophication reduced at early time of experime...