A method for transmitting downlink control information at a network side device configuring a user equipment, UE, with a localized enhanced physical downlink control channel, EPDCCH, set and a distributed EPDCCH set, comprising: selecting, by the network side device, an aggregation level of the localized EPDCCH set and an aggregation level of the distributed EPDCCH set in a transmission subframe; selecting, by the network side device, a number of EPDCCH candidates of the localized EPDCCH set corresponding to the aggregation level of the localized EPDCCH set; selecting, by the network side device, a number of EPDCCH candidates of the distributed EPDCCH set corresponding to the aggregation level of the distributed EPDCCH set; and sending, by the network side device, downlink control information on at least one of: the EPDCCH candidates corresponding to the number of the EPDCCH candidates of the localized EPDCCH set and the EPDCCH candidates corresponding to the number of the EPDCCH candidates of the distributed EPDCCH set; wherein, when the number of resource elements, REs for EPDCCH transmission, in a physical resource block, PRB, pair is smaller than 104, a minimum of aggregation levels of the localized EPDCCH set and the distributed EPDCCH set is 2, the localized EPDCCH set and the distributed EPDCCH set support the aggregation levels 2, 4, 8 and 16 and a sum of the number of the EPDCCH candidates of the localized EPDCCH set and the distributed EPDCCH set is 6 for the aggregation level 2, 6 for the aggregation level 4, 2 for the aggregation level 8 and 2 for the aggregation level 16; and when the number of REs for EPDCCH transmission in the PRB pair is greater than or equal to 104, the localized EPDCCH set and the distributed EPDCCH set support the aggregation levels 1, 2, 4, and 8, the minimum of aggregation levels of the localized EPDCCH set and the distributed EPDCCH set is 1, and the sum of the number of the EPDCCH candidates of the localized EPDCCH set and the distributed EPDCCH set is 6 for the aggregation level 1, 6 for the aggregation level 2, 2 for the aggregation level 4 and 2 for the aggregation level 8. selecting, by the network side device, an aggregation level of the localized EPDCCH set and an aggregation level of the distributed EPDCCH set in a transmission subframe; selecting, by the network side device, a number of EPDCCH candidates of the localized EPDCCH set corresponding to the aggregation level of the localized EPDCCH set; selecting, by the network side device, a number of EPDCCH candidates of the distributed EPDCCH set corresponding to the aggregation level of the distributed EPDCCH set; and sending, by the network side device, downlink control information on at least one of: the EPDCCH candidates corresponding to the number of the EPDCCH candidates of the localized EPDCCH set and the EPDCCH candidates corresponding to the number of the EPDCCH candidates of the distributed EPDCCH set; wherein, when the number of resource elements, REs for EPDCCH transmission, in a physical resource block, PRB, pair is smaller than 104, a minimum of aggregation levels of the localized EPDCCH set and the distributed EPDCCH set is 2, the localized EPDCCH set and the distributed EPDCCH set support the aggregation levels 2, 4, 8 and 16 and a sum of the number of the EPDCCH candidates of the localized EPDCCH set and the distributed EPDCCH set is 6 for the aggregation level 2, 6 for the aggregation level 4, 2 for the aggregation level 8 and 2 for the aggregation level 16; and when the number of REs for EPDCCH transmission in the PRB pair is greater than or equal to 104, the localized EPDCCH set and the distributed EPDCCH set support the aggregation levels 1, 2, 4, and 8, the minimum of aggregation levels of the localized EPDCCH set and the distributed EPDCCH set is 1, and the sum of the number of the EPDCCH candidates of the localized EPDCCH set and the distributed EPDCCH set is 6 for the aggregation level 1, 6 for the aggregation level 2, 2 for the aggregation level 4 and 2 for the aggregation level 8.