A method for transmitting data by using a power line. The method includes: setting i=1 and j=1; receiving an i-th zero crossing signal at a time point ti, and determining, based on the i-th zero crossing signal, a start time when synchronization signals of a j-th data packet are transmitted, the start time when the synchronization signals of the j-th data packet are transmitted being ti+t; transmitting the synchronization signals of the j-th data packet at the start time when the synchronization signals of the j-th data packet are transmitted; transmitting data signals of the j-th data packet in sequence; and determining whether j is equal to M; when j is not equal to M, continuing a data transmission; and when j is equal to M, ending the data transmission, M being a number of data packets into which data to be transmitted is divided.