The cloud computing provides an easy way to access servers storage and databases as well as a wide range of application services over the Internet. Therefore the security is the biggest problem of this system because the services of cloud computing is based on the sharing. Thus a cloud computing environment requires some Intrusion Detection Systems (IDSs) for protecting each machine against attacks. In this book we propose efficient reliable and secure IDS based on multi-agent system for identify and prevent existing known attacks in environment cloud.