The invention discloses a system and method for a smart power grid to transmit GOOSE messages across the wide area network. The system for the smart power grid to transmit the GOOSE messages across the wide area network comprises a sending end and a receiving end. The sending end comprises an encapsulation storage bucket and a first sorting sending bucket, wherein the encapsulation storage bucket is used for receiving the GOOSE messages, carrying out generic routing encapsulation (GRE) on the GOOSE messages, generating an encapsulation sequence number displaying the encapsulation sequence of the GOOSE messages, writing the encapsulation sequence number into a GRE masthead, then carrying out IP encapsulation on the GOOSE messages after the GRE, and generating and storing the IP messages, and the first sorting sending bucket is used for ordering the IP messages in the encapsulation storage bucket according to the encapsulation sequence number and then sending the ordered IP messages to an IP network. The receiving end comprises a de-encapsulation storage bucket and a second sorting sending bucket, wherein the de-encapsulation storage bucket is used for receiving the IP messages from the IP network, carrying out IP de-encapsulation and GRE de-encapsulation on the IP messages to obtain the GOOSE messages, and storing the GOOSE messages obtained after the de-encapsulation, and the second sorting sending bucket is used for ordering the GOOSE messages in the de-encapsulation storage bucket according to the encapsulation sequence number and then sending the ordered GOOSE messages to one or multiple intelligent electronic devices in a transformer substation.