The invention discloses a power line communication frequency spectrum fragment arrangement method and device, and the method comprises the steps: counting continuous unoccupied frequency slot sets of subcarriers, and carrying out ordering according to the number of the continuous unoccupied frequency slot sets; specifying a frequency spectrum space, needing to be emptied, on the continuous unoccupied frequency slot sets, and counting the frequency slot utilization rates of all to-be-emptied subcarriers; selecting the subcarrier frequency spectrum with the maximum frequency slot utilization rate, and providing the subcarrier frequency spectrum with the maximum frequency slot utilization rate for a new business. According to the embodiment of the invention, the method and device improve the continuity of frequency spectrum utilization of an OFDM system in a PLC, and enable occupied frequency spectrums to be compressed within a certain range. The method and device enable unoccupied frequency slots among links to be continuous as much as possible, so as to optimize the utilization condition of resources.