A method for data transmission, implemented by a terminal, the method comprising: receiving a first indication message from a base station, wherein the first indication message comprises first information and the first information is for representing a Packet Data Convergence Protocol, PDCP, packet duplication function and at least two transmission entities configured for a Radio Bearer, RB, by the base station, wherein the at least two transmission entities comprise a primary Radio Link Control, RLC, entity and a secondary RLC entity; setting a transmission function corresponding to the RB to be the PDCP packet duplication function according to the first indication message; setting at least two transmission entities corresponding to the RB according to the at least two transmission entities indicated in the first indication message; setting a present state of the PDCP packet duplication function, the present state comprising an active state and an inactive state; and performing data transmission according to the present state and the transmission entity, characterized in that, the present state of the PDCP packet duplication function is the inactive state, performing the data transmission according to the present state and the transmission entity comprises: in a case that the RB is a newly established signaling radio bearer, SRB, or data radio bearer, DRB, performing the data transmission by use of the primary RLC entity; and in a case that the RB is an SRB or DRB that has been established, adopting at least one of following data transmission manners: performing the data transmission by use of the primary RLC entity for data that is not delivered to an RLC layer and continuing the data transmission by use of the secondary RLC entity for data that has been delivered to the secondary RLC entity, or in an Unacknowledged Mode, UM, performing the data transmission by use of the primary RLC entity for data that is not delivered to the RLC layer. receiving a first indication message from a base station, wherein the first indication message comprises first information and the first information is for representing a Packet Data Convergence Protocol, PDCP, packet duplication function and at least two transmission entities configured for a Radio Bearer, RB, by the base station, wherein the at least two transmission entities comprise a primary Radio Link Control, RLC, entity and a secondary RLC entity; setting a transmission function corresponding to the RB to be the PDCP packet duplication function according to the first indication message; setting at least two transmission entities corresponding to the RB according to the at least two transmission entities indicated in the first indication message; setting a present state of the PDCP packet duplication function, the present state comprising an active state and an inactive state; and performing data transmission according to the present state and the transmission entity, characterized in that, the present state of the PDCP packet duplication function is the inactive state, performing the data transmission according to the present state and the transmission entity comprises: in a case that the RB is a newly established signaling radio bearer, SRB, or data radio bearer, DRB, performing the data transmission by use of the primary RLC entity; and in a case that the RB is an SRB or DRB that has been established, adopting at least one of following data transmission manners: performing the data transmission by use of the primary RLC entity for data that is not delivered to an RLC layer and continuing the data transmission by use of the secondary RLC entity for data that has been delivered to the secondary RLC entity, or in an Unacknowledged Mode, UM, performing the data transmission by use of the primary RLC entity for data that is not delivered to the RLC layer. in a case that the RB is a newly established signaling radio bearer, SRB, or data radio bearer, DRB, performing the data transmission by use of the primary RLC entity; and in a case that the RB is an SRB or DRB that has been established, adopting at least one of following data transmission manners: performing the data transmission by use of the primary RLC entity for data that is not delivered to an RLC layer and continuing the data transmission by use of the secondary RLC entity for data that has been delivered to the secondary RLC entity, or in an Unacknowledged Mode, UM, performing the data transmission by use of the primary RLC entity for data that is not delivered to the RLC layer. performing the data transmission by use of the primary RLC entity for data that is not delivered to an RLC layer and continuing the data transmission by use of the secondary RLC entity for data that has been delivered to the secondary RLC entity, or in an Unacknowledged Mode, UM, performing the data transmission by use of the primary RLC entity for data that is not delivered to the RLC layer.