The invention provides a remote data communication system. The remote data communication system comprises a request client side, an authentication server, a database server and a relay server, wherein the authentication server is used for inquiring account information and an associated IP (internet protocol) address of the client side to the database server according to request messages of the request client side; the database server is used for sending an available IP address of the relay server to the authentication server and sending the IP address of the relay server to the request client side by the authentication server; and the relay server is used for inquiring the account information of the request client side to the database server after being connected with the request client side. Authentication passes if the database server includes corresponding information, a VPN (virtual private network) channel between the relay server and the request client side is established after authentication is passed, and the request client side is informed of the assigned virtual IP address, so that simple and transparent interconnection and intercommunication among devices can become possible.