Control method for network switching of mobile terminal, mobile terminal and system

This invention puts forward a multi-network card mobile terminal used in switching among different networks and a switching method including: multiple network interfaces connecting to multiple different networks, a switching unit switching multiple network interfaces to select different networks for communication, a switch control unit dividing all packets sent to networks into data packets and message packets relating to switch and sending the data packets to the current network and sending the message packets relating to switch to all networks to be connected when switching networks and sending all of them to a target network after receiving the message of allowing switching networks then to cut off connection with the current network.