The invention relates to a broadband power line communication method, in particular to a 35 kv-voltage grade line-based long-distance high-speed broadband power line communication method. The method comprises the following steps of: first, arranging a power communication device on a power line and coupling signals to the power line in a wired way; then, transmitting radio carrier signals to space according to high-voltage power line characteristics; and finally, receiving radio signals in a wireless way. Technicians overcome technical prejudices in the field, the radio signals transmitted by the power line and an antenna are acquired by a thought of taking the power line as the antenna and by adopting the method of transmitting by using the power line directly and receiving by using the antenna, so that the communication distance is expanded over 8 km successfully and effectively; therefore, the broadband power line communication with the first-stage relay of 14.5 KM is realized.