A method for transmitting acknowledgement/negative acknowledgement, ACK/NACK, information in a long term evolution, LTE, system, applicable for a situation that uplink-downlink configurations of multiple serving cells of a carrier aggregation, CA, are different, comprising: receiving, by a user equipment, UE, an uplink, UL, grant of a first serving cell to the UE, the UL grant including an UL downlink assignment index, DAI, from a node B; obtaining, by the UE, the UL DAI in the UL grant; and transmitting, by the UE, ACK/NACK information on a physical uplink shared channel, PUSCH, wherein a length of the ACK/NACK information is determined according to the value of the UL DAI of a first serving cell, wherein the first serving cell is the serving cell among the multiple serving cells that the PUSCH belongs to, wherein, if a transmission mode of the first serving cell is single input multiple output, SIMO, the length of the ACK/NACK information of the first serving cell equals to the value of the UL DAI of the first serving cell, and wherein, if the transmission mode of the first serving cell is multiple input multiple output, MIMO, the length of the ACK/NACK information of the first serving cell is twice of the value of the UL DAI of the first serving cell, wherein, if a transmission mode of a second serving cell is SIMO, a length of the ACK/NACK information of the second serving cell equals to a minimum of the value of the UL DAI value in the UL grant of the first serving cell and the size of ACK/NACK bundling window of the second serving cell, and wherein, if the transmission mode of the second serving cell is MIMO, the length of the ACK/NACK information of the second serving cell is twice of the minimum of the value of the UL DAI value in the UL grant of the first serving cell and the size of the ACK/NACK bundling window of the second serving cell, wherein the sum of the lengths of ACK/NACK information of all serving cells in the CA is the length of the ACK/NACK information transmitted on the PUSCH. receiving, by a user equipment, UE, an uplink, UL, grant of a first serving cell to the UE, the UL grant including an UL downlink assignment index, DAI, from a node B; obtaining, by the UE, the UL DAI in the UL grant; and transmitting, by the UE, ACK/NACK information on a physical uplink shared channel, PUSCH, wherein a length of the ACK/NACK information is determined according to the value of the UL DAI of a first serving cell, wherein the first serving cell is the serving cell among the multiple serving cells that the PUSCH belongs to, wherein, if a transmission mode of the first serving cell is single input multiple output, SIMO, the length of the ACK/NACK information of the first serving cell equals to the value of the UL DAI of the first serving cell, and wherein, if the transmission mode of the first serving cell is multiple input multiple output, MIMO, the length of the ACK/NACK information of the first serving cell is twice of the value of the UL DAI of the first serving cell, wherein, if a transmission mode of a second serving cell is SIMO, a length of the ACK/NACK information of the second serving cell equals to a minimum of the value of the UL DAI value in the UL grant of the first serving cell and the size of ACK/NACK bundling window of the second serving cell, and wherein, if the transmission mode of the second serving cell is MIMO, the length of the ACK/NACK information of the second serving cell is twice of the minimum of the value of the UL DAI value in the UL grant of the first serving cell and the size of the ACK/NACK bundling window of the second serving cell, wherein the sum of the lengths of ACK/NACK information of all serving cells in the CA is the length of the ACK/NACK information transmitted on the PUSCH.