Abstract: Nano-science is one of 3 pillars in the fields of 21^st century scientific studies. Because of their unique and superior quantum sizes and surface effects as well as other characteristics, nanomaterials are extensively applied for industrial, medical, and general applications. Thus, the ecotoxicology of nanomaterials has become an issue that draws increasing attentions. Aquatic ecosystem is subject to pollution by a wide varieties of sources with substances, including nanomaterials, released from rainfalls, surface runoff, underground seepage, and waste water discharge. Consequently, inland freshwater is likely most vulnerable to the serious damages introduced by the discharged nanomaterials. Impacts on the physiology of freshwater aquatic organisms cannot be overlooked. This article summarizes the properties of nanomaterials, and analyzes relevant approaches to mitigate the harmful effects on the eco-system.It reviews the 3 common classes of the materials, and the current research status and progress with an emphasis on nano metal oxide. Finally, the anticipated direction and proposals for future studies relating to the biotoxicity and safety of the ever-increasingly popular material are discussed.