A method for processing a Radio Link Failure, RLF, comprising: duplicating, by a terminal device, a first Packet Data Convergence Protocol, PDCP, Protocol Data Unit, PDU, which is to be sent to a network device, so as to obtain a second PDCP PDU; sending, by the terminal device, the first PDCP PDU and the second PDCP PDU to a first Radio Link Control, RLC, entity and a second RLC entity, respectively, wherein the first and second RLC entities process and send the first and second PDCU PDUs to a network device using a primary carrier and a secondary carrier, respectively; if the number of transmissions of Acknowledged Mode Protocol Data Unit, AMD, PDU, reaches the maximum number of transmissions in the second RLC entity corresponding to the secondary carrier, determining by the terminal device that an RLF event occurs in the secondary carrier; and sending (S 130), by the terminal device, first RLF type indication information to the network device; wherein the primary carrier is a primary carrier in a Secondary Cell Group, SCG, and the secondary carrier is a secondary carrier in the SCG, wherein the first RLF type indication information is used to indicate that a carrier where the RLF event occurs is the secondary carrier in the SCG; wherein the method further comprises: if the number of transmissions of the AMD PDU reaches the maximum number of transmissions in the RLC entity corresponding to the primary carrier in the SCG, determining by the terminal device that the RLF event occurs in the primary carrier in the SCG; and sending, by the terminal device, second RLF type indication information to the network device, wherein the second RLF type indication information is used to indicate that the carrier where the RLF event occurs is the primary carrier in the SCG. duplicating, by a terminal device, a first Packet Data Convergence Protocol, PDCP, Protocol Data Unit, PDU, which is to be sent to a network device, so as to obtain a second PDCP PDU; sending, by the terminal device, the first PDCP PDU and the second PDCP PDU to a first Radio Link Control, RLC, entity and a second RLC entity, respectively, wherein the first and second RLC entities process and send the first and second PDCU PDUs to a network device using a primary carrier and a secondary carrier, respectively; if the number of transmissions of Acknowledged Mode Protocol Data Unit, AMD, PDU, reaches the maximum number of transmissions in the second RLC entity corresponding to the secondary carrier, determining by the terminal device that an RLF event occurs in the secondary carrier; and sending (S 130), by the terminal device, first RLF type indication information to the network device; wherein the primary carrier is a primary carrier in a Secondary Cell Group, SCG, and the secondary carrier is a secondary carrier in the SCG, wherein the first RLF type indication information is used to indicate that a carrier where the RLF event occurs is the secondary carrier in the SCG; wherein the method further comprises: if the number of transmissions of the AMD PDU reaches the maximum number of transmissions in the RLC entity corresponding to the primary carrier in the SCG, determining by the terminal device that the RLF event occurs in the primary carrier in the SCG; and sending, by the terminal device, second RLF type indication information to the network device, wherein the second RLF type indication information is used to indicate that the carrier where the RLF event occurs is the primary carrier in the SCG. if the number of transmissions of the AMD PDU reaches the maximum number of transmissions in the RLC entity corresponding to the primary carrier in the SCG, determining by the terminal device that the RLF event occurs in the primary carrier in the SCG; and sending, by the terminal device, second RLF type indication information to the network device, wherein the second RLF type indication information is used to indicate that the carrier where the RLF event occurs is the primary carrier in the SCG.