The embodiment of the invention provides a virtual machine migration method and device. The method comprises the steps that the memory information of each virtual machine in the machine is acquired; when the load of the machine is too heavy, a virtual machine migration request is generated, and candidate servers and the memory information thereof are acquired; the memory information of each virtual machine and the memory information of the candidate servers are compared, so that the virtual machine needing migration in the machine is determined and a target server is selected from the candidate servers; and the virtual machine needing migration in the machine is migrated to the selected target server. According to the embodiment of the invention, a system has a high memory utilization rate after virtual machine migration; the sharp increasing of a physical memory requirement is avoided; and when the memory load of a server is too heavy, the server can acquire desired idle memory after virtual machine migration.