A user equipment (UE) and a base station (BS) are provided. The UE monitors a plurality of semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) resources, and determines an SPS Hybrid Automatic Repeat reQuest acknowledge (HARQ-ACK) bit order of a plurality of SPS HARQ-ACK bits, corresponding to the SPS PDSCH resources, in a codebook according to a time-domain position, a component carrier index and a configuration index of each SPS PDSCH resource. Afterwards, the UE generates an HARQ-ACK message including the codebook according to the SPS HARQ-ACK bit order, and transmits the HARQ-ACK message on a physical uplink control channel (PUCCH) resource to the BS.