The invention discloses a TCP transparent agent realization method facing an electric power IEC104 protocol. The method comprises following steps that S1: a client end gateway encryption device obtains report information with serial numbers sent by an IEC104 client end, and sends the report information to a server gateway encryption device and then an IEC104 server; S2: the client end gateway encryption device generates gateway serial numbers, the server gateway encryption device establishes a tunnel and communication reports with gateway serial numbers are sent to the server gateway encryption device irregularly; S3: the IEC104 client end sends the report information with the serial numbers and the client end generates gateway serial numbers according to the serial numbers, encrypts and combines the report information into processing information, and sends the processing information to the server gateway encryption device; and S4: the server network encryption device carries out reverse processing on the gateway serial numbers, decrypts the report information and sent the decrypted report information to the IEC104 server. In this way, a safety problem in cleartext transportation of the IEC104 report information is effectively solved.