Provided in embodiments of the present application are a method of supporting data replication, transmitting terminal device and receiving terminal device capable of realizing reliable transmission of replicated data in a vehicle-to-everything system. The method comprises: a transmitting terminal device transmitting a plurality of radio link control protocol data units (RLC PDUs) to a receiving terminal device, an RLC header of at least one RLC PDU in the plurality of RLC PDUs comprising an indication field for indicating a radio bearer corresponding to a current RLC PDU.