Virtual machine on-line transfer method across virtualization data centers

The invention provides a virtual machine on-line transfer method across virtualization data centers. The method includes that step 1, a plurality of virtualization data centers are deployed on a wide area network (WAN), and each virtual machine mirror file is divided into a template and user private data files, step 2, the virtualization data centers are connected through a virtual private network (VPN) of a two-tier bridge pattern, step 3, dirty blocks written into a disk every time are monitored in a virtual machine input/output (I/O) drive course on a source node, a transfer thread is created for the drive course, and the transfer thread pre-transfers the user private data files and transfers monitoring records of the dirty blocks, step 4, a transfer course of a virtual machine on the source node controls the pre-transfer and the transfer of the monitoring record, and step 5, the execution sequence of a destination node recovery course of the virtual machine is changed, a recovery thread is created for the recovery course, and the recovery thread receives information about the pre-transfer and the transfer of the monitoring records and writes the information into a storage node. The virtual machine on-line transfer method across the virtualization data centers can achieve dynamic mapping of virtual machines and resources among the plurality of virtualization data centers.