The application pertains to a method for communicating a downlink control signal. A base station maps a physical downlink control channel (PDCCH) sequentially to resource elements for transmitting the PDCCH in each orthogonal frequency division multiplexing (OFDM) symbol according to an order of OFDM symbols used by the PDCCH of a user equipment (UE). The PDCCH is sent to the UE from the base station by using the resource elements. Because the PDCCH is mapped sequentially to resource elements for transmitting the PDCCH in each OFDM symbol according to an order of OFDM symbols used by the PDCCH of the UE, different control channel elements of PDCCHs at different aggregation levels will not include a same PDCCH modulation symbol, thereby ensuring that the UE judges a start position of the PDCCH correctly.