A virtual machine migration method, applied to a virtual machine system, wherein the virtual machine system comprises a virtual machine migration management unit, a host device, and a physical network interface card; at least one virtual machine runs on the host device, at least one virtual network interface card runs on the physical network interface card, each virtual machine corresponds to at least one virtual network interface card, and the physical network interface card reads and writes data in a memory of each virtual machine in a direct memory access manner; and the method comprises: receiving, by a to-be-migrated source virtual machine, a message for starting virtual machine migration that is sent by the virtual machine migration management unit; setting, by the source virtual machine, a dirty write flag according to the message for starting virtual machine migration; when it is determined that the physical network interface card writes new data into a memory of the source virtual machine and the dirty write flag has been set, reading, by the source virtual machine, the new data from the memory of the source virtual machine according to the dirty write flag, and writing the new data into the memory of the source virtual machine again; receiving, by the source virtual machine, a message for shutting down the source virtual machine that is sent by the virtual machine migration management unit; writing, by the source virtual machine after receiving the message for shutting down the source virtual machine, status information of a virtual network interface card corresponding to the source virtual machine into the memory of the source virtual machine; and triggering, by the virtual machine migration management unit, a memory iteration operation, wherein the memory iteration operation is used to migrate the new data in the memory of the source virtual machine to a destination virtual machine; and clearing, by the source virtual machine, the dirty write flag. receiving, by a to-be-migrated source virtual machine, a message for starting virtual machine migration that is sent by the virtual machine migration management unit; setting, by the source virtual machine, a dirty write flag according to the message for starting virtual machine migration; when it is determined that the physical network interface card writes new data into a memory of the source virtual machine and the dirty write flag has been set, reading, by the source virtual machine, the new data from the memory of the source virtual machine according to the dirty write flag, and writing the new data into the memory of the source virtual machine again; receiving, by the source virtual machine, a message for shutting down the source virtual machine that is sent by the virtual machine migration management unit; writing, by the source virtual machine after receiving the message for shutting down the source virtual machine, status information of a virtual network interface card corresponding to the source virtual machine into the memory of the source virtual machine; and triggering, by the virtual machine migration management unit, a memory iteration operation, wherein the memory iteration operation is used to migrate the new data in the memory of the source virtual machine to a destination virtual machine; and clearing, by the source virtual machine, the dirty write flag.