The invention relates to a system for detecting an electronic tag on a low voltage current transformer calibration line and a method thereof. The system comprises a conveying belt, a stop position, a barcode scanner, an RFID antenna, an RFID reader-writer, a secret key management unit, an electric control programmable logic controller PLC, a host, a displayer and a metal shell. The detection method comprises the steps that the RFID reader-writer performs identity authentication on the electronic tag and performs MAC authentication on the information stored in the read electronic tag and compares the information through MAC authentication and barcode information of the electronic tag read by the barcode scanner; as for the successfully compared electronic tag, transformer calibration information of the electronic tag is read from a database server by the host, the calibration information is encrypted by using the secret key management unit and the RFID reader-writer is controlled to write encryption information in the electronic tag and perform authentication; and the host acquires an electronic tag transaction secret key from the secret key management unit and controls the RFID reader-writer to write the transaction secret key in the electronic tag and perform identity authentication.