A method of setting retransmission time of an application client during virtual machine migration includes predicting migration memory size required by a virtual machine to be migrated based on historical access log of at least one application and memory log of the virtual machine to be migrated; computing available migration bandwidth of a host of the virtual machine to be migrated; computing virtual machine migration time based on the predicted migration memory size required by the virtual machine to be migrated and the available migration bandwidth of the host; and setting retransmission time of the application client based on the virtual machine migration time.