Provided are a sidelink relay communication method and apparatus, a device, and a medium. The sidelink relay communication method is applied to user equipment (UE)-to-Network relay communication. The method includes the following processes. The relay UE receives a data packet from a source communication device through a first bearer between the source communication device and the relay UE, where the data packet is mapped to the first bearer by the source communication device. The relay UE maps the data packet to a second bearer between the relay UE and a target communication device and transmits the data packet to the target communication device, where either the source communication device comprises a remote UE and the target communication device comprises a base station or the source communication device comprises a base station and the target communication device comprises a remote UE.