Being the basis of human society, freshwater aqua-ecosy stem is suffering of gradual degradation in many regions of the world.Most fresh water lakes and river net in plain are shallow waters in China.There are abundant higher aquatic plants and associated fish, shrimp, shellfish, mussel and other macro-hydroorg anisms.Possessing prolif ic biodiversity, these waters were selected as drinking water sources for many cities and tow ns in the history.But at present, these clear waters in most cases have been degenerating into "desert-waters" in defectof macrophy tes but dominated by phy toplankton and other microorganisms, along with the increase of pollutant loading.The loading of pollutions into surface water systems was increased gradually in comparison with that before a couple of decades ago.How to restore the degenerated aquaecosystem for a sustainable and healthy aquaecosystem under enhanced pollutants loading is the issue of great theoretical and practical importance.The water quality problem is a problem of ecosy stem.The target, measures, approaches, key technologies and the feasibility for remediation of the aquaecosy stem were reported in this paper according to the research and experiment results on Physico-Ecological Engineering(PEEN) in fresh waters of China since 1990 [1].The main conclusions are as follows:1)The main aim for harnessing the surface waters is remediation for sustainable healthy aquaecosystems.2)The main measures for harnessing the surface waters are to carry out the Physico-Ecological Engineering-(PEEN)and Bio-Envio ronmental Enterprise-(BEE)in combine with harnessing the pollution sources.3)The main approach for realizing the aim is "sparks ex ploding" starting from local to larger areas and to the whole catchment.4)The key momentums for realizing the aim are 4M:Macrophyte, Macro bio-imitation, Microo rganism, and Management.5)The beautiful and bright future with green mountains, clean waters, high level waters, high level civilization and abundant resources in harmony developmentof social economy and environment might be realized come-atable.