The embodiment of the invention provides a message data processing method and a message data processing device. The method is applied to a first gateway, and the method comprises the following steps:receiving first message data of a first network device which is located in the same local area network with the first gateway; when a destination address in the first message data is the address of asecond network device which is located in a different local area network with the first network device, determining the address of a second gateway which is in a public network address binding relation with the second network device; according to the address of the second gateway, performing routing forwarding for the second message data formed through compiling and packaging the first message again; and by a preestablished virtual private network VPN channel of IPsec, sending the second message data to the second gateway. The method and the device provided by the embodiment of the invention realize remote resource calling, and improve confidentiality in a processing process due to high security of the IPsec; and the data is transmitted through the VPN channel, thus, increase of hardware cost is avoided.