The human activity causing eutrophication,and worsening the water quality,has resulted in a great number of death of fish and aquatic animals and hydrophytes.The prevention and cure of eutrophication are the most complex and difficult problems in the water treatment.Because of the difficulty of treatment,so far there has been no measure to eliminate the nourishment like nitrogen and phosphorus in grain by single measure of biological,chemical or physical treatment.The control standard of nitrogen and phosphorus in the current water,technique of denitrogenation and dephosphorization (techniques of biological nitrification,denitrification,biological dephosphorization etc.) in sewage are introduced.Several typical project instances of surface water and sewage treatment in Germany are enumerated.