A Gigabit Ethernet passive optical network (GE-PON) and method for accurately detecting an error of data to securely transmit the data. The GE-PON comprises an optical line terminal (OLT) for performing first error checking of an Ethernet frame before encrypting original data content in the Ethernet frame, appending a first error detection code resulting from the first error checking to the Ethernet frame, encrypting the original data content, performing second error checking of the appended Ethernet frame containing the encrypted data, appending a second error detection code resulting from the second error checking to the appended Ethernet frame containing the encrypted data and transmitting the resulting Ethernet frame with the encrypted data, the first error correction code and the second error correction code to at least one destination, and at least one optical network terminal (ONT) for checking a transmission error of the received Ethernet frame containing the encrypted data, the first error correction code and the second error correction code transmitted from the OLT using the second error detection code, decrypting the encrypted data and checking an encryption error and decryption error of the resulting Ethernet frame with the decrypted data using the first error detection code.