With the development of the computer technology, the virtual machine has been become the main research topic. Understanding of the current technology and future trends of virtual machine system greatly help to improve the service performance of system. Therefore, we describe the current technology and present the future trends of virtual machine system in the paper. In the current technology of virtual machine system, we mainly describe the virtualization technology, the resource scheduling technology, the migration technology, the security technology and the performance evaluation technology. In the future trends of virtual machine system, we mainly present an overview of the future CPU architecture, the management mode of future memory and resource, the future maintaining method of system security and the performance evaluation method of future multiple virtual machine system.