A user equipment (UE) and a method for packet data convergence protocol (PDCP) duplication are provided. The method includes receiving, from a base station (BS), a radio resource control (RRC) message configuring a logical channel with a logical channel prioritization (LCP) restriction and configuring the logical channel to be associated with a data radio bearer (DRB) configured with a PDCP duplication function, wherein the PDCP duplication function is associated with a first cell group; receiving, from the BS, an uplink (UL) grant indicating a UL resource on a serving cell; initiating an LCP procedure for generating a protocol data unit (PDU) to be transmitted on the UL resource; and determining whether to apply the LCP restriction during the LCP procedure upon determining that the PDCP duplication function is deactivated.