In order to reveal the trophic state of lakes and reservoirs in China and lay a scientific foundation for lake water resources protection, the first synchro investigation of wide scope into water quality of 26 lakes was carried out by a lot of scientists.The investigated items were important parameters correlating to trophic state of lakes, such as pH, water temperature, transpancy, DO, COD, NH4
-N, TP, TN, PO4
3-P, Chl-a, Mn, Fe and so on.In the light of the investigated results, a few of the most important water quality parameters were selected to characterise the trophic state of the main lakes and reservoirs in China.Based on the distributions and rules of trophic pollution (pH, SD, DO, TP . TN ect.),we made correlatively statstical analysis and established correlative relation among these items. The study provided scientific basis for management and harnessing of lakes in China.