A mobile network communications method, wherein the method comprises: receiving, by a transport packet data network gateway, a data packet to be sent to a mobile node, wherein the data packet carries IP address information of the mobile node; determining, by the transport packet data network gateway, a home packet data network gateway of the mobile node according to the IP address information of the mobile node; sending, by the transport packet data network gateway, a data connection establishment request message to the home packet data network gateway, to request to establish a data connection to a base station or a serving gateway at a location of the mobile node, and receiving, by the transport packet data network gateway, a data connection establishment response message, so that a transport packet data network gateway establishes the data connection to the base station or the serving gateway by using the home packet data network gateway, wherein the transport packet data network gateway stores information about all IP address segments in an entire mobile network that are used for being assigned to a mobile node, and the transport packet data network gateway notifies all nearby network nodes of the information about all IP address segments that are used for being assigned to a mobile node, so that a correspondent node can access the mobile network by using the transport packet data network gateway; and sending, by a transport packet data network gateway, the data packet to the base station or the serving gateway through a channel of the data connection, or receiving a data packet that is sent by the base station or the serving gateway through a channel of the data connection, wherein the data packet is transferred through the channel of the data connection without passing through the home packet data network gateway. receiving, by a transport packet data network gateway, a data packet to be sent to a mobile node, wherein the data packet carries IP address information of the mobile node; determining, by the transport packet data network gateway, a home packet data network gateway of the mobile node according to the IP address information of the mobile node; sending, by the transport packet data network gateway, a data connection establishment request message to the home packet data network gateway, to request to establish a data connection to a base station or a serving gateway at a location of the mobile node, and receiving, by the transport packet data network gateway, a data connection establishment response message, so that a transport packet data network gateway establishes the data connection to the base station or the serving gateway by using the home packet data network gateway, wherein the transport packet data network gateway stores information about all IP address segments in an entire mobile network that are used for being assigned to a mobile node, and the transport packet data network gateway notifies all nearby network nodes of the information about all IP address segments that are used for being assigned to a mobile node, so that a correspondent node can access the mobile network by using the transport packet data network gateway; and sending, by a transport packet data network gateway, the data packet to the base station or the serving gateway through a channel of the data connection, or receiving a data packet that is sent by the base station or the serving gateway through a channel of the data connection, wherein the data packet is transferred through the channel of the data connection without passing through the home packet data network gateway.