This application provides a method for multiplexing uplink control information, and relates to the wireless communications field. When a resource of a first uplink control channel that carries first HARQ-ACK information does not overlap a resource of a second uplink control channel that carries second HARQ-ACK information in time domain, but a resource of a third uplink control channel that carries an SR/CSI overlaps both the resource of the first uplink control channel and the resource of the second uplink control channel in time domain, a base station and UE determine, based on a format of the first uplink control channel, a format of the second uplink control channel, and a format of the third uplink control channel, that third HARQ-ACK information and first UCI are multiplexed for transmission, where the third HARQ-ACK information is the first HARQ-ACK information or the second HARQ-ACK information.