Provided in the present invention is a power-line carrier communication method, comprising a preamble sequence-based low-speed robust communication method. The robust communication method provides an auxiliary communication mode when effective communication cannot be provided by a conventional communication mode in a harsh channel environment. Based on a preamble signal and a processing method therefor, the method allows timing and synchronization in a packet-switched data network. When normal communication cannot be carried out under the conventional communication mode, communication via the robust communication mode is attempted. The robust communication mode provided in the present invention is capable of providing low-speed and reliable communication when the conventional communication mode cannot work reliably, thus satisfying basic communication requirements of a network, and reducing network failure rate.