A method for sidelink data duplication function control, performed by a first terminal device and comprising: receiving (S201), from a higher layer, one or more data flows to be sent to a second terminal device ; and activating or deactivating, based on a preset rule, data duplication function of a sidelink radio bearer, SLRB, between the first terminal device and the second terminal device , characterized in that the preset rule comprises whether at least one of data flows satisfies a preset quality of service, QoS, condition, wherein the activating or deactivating, based on the preset rule, data duplication function of the SLRB between the first terminal device and the second terminal device comprises: activating or deactivating data duplication function between the first terminal device and the second terminal device based on the preset rule and a control granularity of SLRB data duplication function, wherein the control granularity is link level; wherein the activating or deactivating data duplication function of the SLRB between the first terminal device and the second terminal device based on the preset rule and the control granularity of SLRB data duplication function comprises: if all of data flows mapped to a target communication link satisfy the preset QoS condition, activating data duplication function of all SLRBs on the target communication link, wherein the target communication link includes one or more communication links between the first terminal device and the second terminal device . receiving (S201), from a higher layer, one or more data flows to be sent to a second terminal device ; and activating or deactivating, based on a preset rule, data duplication function of a sidelink radio bearer, SLRB, between the first terminal device and the second terminal device , characterized in that the preset rule comprises whether at least one of data flows satisfies a preset quality of service, QoS, condition, wherein the activating or deactivating, based on the preset rule, data duplication function of the SLRB between the first terminal device and the second terminal device comprises: activating or deactivating data duplication function between the first terminal device and the second terminal device based on the preset rule and a control granularity of SLRB data duplication function, wherein the control granularity is link level; wherein the activating or deactivating data duplication function of the SLRB between the first terminal device and the second terminal device based on the preset rule and the control granularity of SLRB data duplication function comprises: if all of data flows mapped to a target communication link satisfy the preset QoS condition, activating data duplication function of all SLRBs on the target communication link, wherein the target communication link includes one or more communication links between the first terminal device and the second terminal device . activating or deactivating data duplication function between the first terminal device and the second terminal device based on the preset rule and a control granularity of SLRB data duplication function, wherein the control granularity is link level; wherein the activating or deactivating data duplication function of the SLRB between the first terminal device and the second terminal device based on the preset rule and the control granularity of SLRB data duplication function comprises: if all of data flows mapped to a target communication link satisfy the preset QoS condition, activating data duplication function of all SLRBs on the target communication link, wherein the target communication link includes one or more communication links between the first terminal device and the second terminal device . <EOS>