Nanotechnology has brought huge economic benefits and social changes, while the uncertainty and risks of nanotechnology has also brought negative effects.This paper based on science and technology ethics to demonstrate that nanotechnology has four main negative impacts, including nano materials toxicity issues, interests and risk diversification issues, nano weapons issues and biomedical ethics issues of nanotechnology.Then demonstrates that S T and ethics are mutual influence and their relationship is indispensable and dialectical.And It is necessary to use S T ethics to constrain nanotechnology “goodness” development.Finally, this paper puts forward countermeasures to the ethical problems caused by nanotechnology.