\[Abstract\]Nano-materials have been increasingly widely used in various fields with the progression in science and technology. While bringing benefit to our life, their toxic effects also come to our attention. In this paper we review the cytotoxic effects and some problems of several kinds of nano-materials (carbon-based nano-materials, metal and metallic oxides and other nano-materials), considering the physicochemical characteristics of nano-materials, research methods of the nano-material cytotoxic effects, and the cytotoxcity of nano-materials. Finally, we also discuss the research focus of the area and issues need to be addressed, hoping to provide a guide for bio-safety research of nano-materials.