Embodiments of the present invention provide a method, an apparatus, and a system for multi-carrier OFDM duplex transmission, and relate to the communications field, so as to solve the problem where spectrum duplex transmission cannot be normally performed due to interference that is generated by an echo signal transmitted by using an OFDM technology. The method for multi-carrier OFDM duplex transmission includes: performing, on at least one OFDM subcarrier channel, sending and receiving of a near-end OFDM signal; obtaining a carrier phase difference between a near-end echo OFDM signal and a far-end OFDM signal; and performing a phase adjustment for the near-end OFDM signal according to the carrier phase difference.