A method for transmitting downlink control information DCI, characterized by comprising: a base station configuring a physical downlink shared channel PDSCH carrier set for a user equipment UE; when the base station determining it is not configured with a carrier indicator field, the base station transmitting a physical downlink control channel PDCCH on each downlink component carrier within the PDSCH carrier set, the PDCCH bearing corresponding DCI; and the UE detecting the corresponding DCI on each downlink component carrier within the PDSCH carrier set; said method characterized by: the base station configuring a physical downlink control channel carrier set for a user equipment UE, wherein the PDCCH carrier set is divided into a UE-specific DCI carrier set and a public DCI carrier set respectively indicating the downlink component carriers of the UE-specific DCI and public DCI that the UE needs to detect; when the base station determining it is configured with the carrier indicator field, the base station transmitting a physical downlink control channel PDCCH bearing corresponding DCI on each downlink component carrier within the PDCCH carrier set divided into the UE-specific DCI carrier set and the public DCI carrier set; and the UE detecting corresponding UE specific DCI in UE-specific search space of each downlink component carrier within the UE-specific DCI carrier set, and the UE detecting corresponding public DCI in common search space of each downlink component carrier within the public DCI carrier set. a base station configuring a physical downlink shared channel PDSCH carrier set for a user equipment UE; when the base station determining it is not configured with a carrier indicator field, the base station transmitting a physical downlink control channel PDCCH on each downlink component carrier within the PDSCH carrier set, the PDCCH bearing corresponding DCI; and the UE detecting the corresponding DCI on each downlink component carrier within the PDSCH carrier set; said method characterized by: the base station configuring a physical downlink control channel carrier set for a user equipment UE, wherein the PDCCH carrier set is divided into a UE-specific DCI carrier set and a public DCI carrier set respectively indicating the downlink component carriers of the UE-specific DCI and public DCI that the UE needs to detect; when the base station determining it is configured with the carrier indicator field, the base station transmitting a physical downlink control channel PDCCH bearing corresponding DCI on each downlink component carrier within the PDCCH carrier set divided into the UE-specific DCI carrier set and the public DCI carrier set; and the UE detecting corresponding UE specific DCI in UE-specific search space of each downlink component carrier within the UE-specific DCI carrier set, and the UE detecting corresponding public DCI in common search space of each downlink component carrier within the public DCI carrier set. the base station configuring a physical downlink control channel carrier set for a user equipment UE, wherein the PDCCH carrier set is divided into a UE-specific DCI carrier set and a public DCI carrier set respectively indicating the downlink component carriers of the UE-specific DCI and public DCI that the UE needs to detect; when the base station determining it is configured with the carrier indicator field, the base station transmitting a physical downlink control channel PDCCH bearing corresponding DCI on each downlink component carrier within the PDCCH carrier set divided into the UE-specific DCI carrier set and the public DCI carrier set; and the UE detecting corresponding UE specific DCI in UE-specific search space of each downlink component carrier within the UE-specific DCI carrier set, and the UE detecting corresponding public DCI in common search space of each downlink component carrier within the public DCI carrier set.