The invention relates to a method for optimizing multiple-network-interface transmission of a message of an intelligent substation. The method comprises the following steps: configuring a source MAC (media access control) address of each network interface to an FPGA (field programmable gate array) and preparing to transmit an Ethernet message which is a multi-packet message, wherein each packet of the message comprises a message packet head, message data and a message packet tail; generating an MAC effective zone bit by a CPU (central processing unit); transmitting the MAC effective zone bit, the message head, the message data and the message packet tail to the FPGA sequentially; unpacking the packet message by the FPGA; transmitting the message data of the MAC effective label to an MAC source address processing module of a corresponding MAC according to the analyzed MAC effect zone bit; and after inserting an source MAC address of the MAC in the message data to be transmitted through the MAC source address processing module, transmitting by the FPGA. The method for optimizing the multiple-network-interface transmission of the message of the intelligent substation, disclosed by the invention, has the advantages of improving the transmission efficiency of an interface, reducing the development difficulty of the CPU and reducing the received data quantity of the PFGA.