With the rapid development of network information, a new term is widely used , that is,"Cloud Computing." It will completely change habit that the desktop as the core, and transferred to the core of Web, use storage and services on web. Humans may enter a new information age. So "Cloud Security" has also been more and more people are concerned. "Cloud Security" combines the parallel processing, grid computing, the Judgement of unknown viruses and other emerging technologies and concepts, through the mass of the network client detect status of all abnormal behavior and obtain the latest information of Trojans, viruses and other undesirable program, sent information to the server for automatic analysis and processing, then solutions in turn distributed to each client to solve insecurity.