A method for quality of service, QoS, parameter configuration, the method comprising: obtaining , by a first device, a mapping between a first QoS parameter and a second QoS parameter, wherein the mapping between the first QoS parameter and the second QoS parameter is configured through packet data unit, PDU, session signaling, wherein obtaining, by the first device, the mapping between the first QoS parameter and the second QoS parameter comprises: receiving, by the first device, a PDU session establishment response from a network device after transmitting a PDU session establishment request to the network device, wherein the PDU session establishment response contains the mapping between the first QoS parameter and the second QoS parameter; wherein the first QoS parameter is applied to a first QoS flow, and the second QoS parameter is applied to a second QoS flow, wherein the first QoS flow is a QoS flow between the first device and the network device, and the second QoS flow is a QoS flow between the first device and a second device; wherein the first QoS parameter comprises a 5 th generation, 5G, QoS index, 5QI, and the second QoS parameter comprises a PC5 QoS index, PQI, wherein the mapping between the first QoS parameter and the second QoS parameter comprises a mapping between the 5QI and the PQI; wherein the method further comprises: before obtaining, by the first device, the mapping between the first QoS parameter and the second QoS parameter, transmitting, by the first device, first capability indication information to the network device, wherein the first capability indication information is used for indicating that the first device supports a relay service. obtaining , by a first device, a mapping between a first QoS parameter and a second QoS parameter, wherein the mapping between the first QoS parameter and the second QoS parameter is configured through packet data unit, PDU, session signaling, wherein obtaining, by the first device, the mapping between the first QoS parameter and the second QoS parameter comprises: receiving, by the first device, a PDU session establishment response from a network device after transmitting a PDU session establishment request to the network device, wherein the PDU session establishment response contains the mapping between the first QoS parameter and the second QoS parameter; wherein the first QoS parameter is applied to a first QoS flow, and the second QoS parameter is applied to a second QoS flow, wherein the first QoS flow is a QoS flow between the first device and the network device, and the second QoS flow is a QoS flow between the first device and a second device; wherein the first QoS parameter comprises a 5 th generation, 5G, QoS index, 5QI, and the second QoS parameter comprises a PC5 QoS index, PQI, wherein the mapping between the first QoS parameter and the second QoS parameter comprises a mapping between the 5QI and the PQI; wherein the method further comprises: before obtaining, by the first device, the mapping between the first QoS parameter and the second QoS parameter, transmitting, by the first device, first capability indication information to the network device, wherein the first capability indication information is used for indicating that the first device supports a relay service. before obtaining, by the first device, the mapping between the first QoS parameter and the second QoS parameter, transmitting, by the first device, first capability indication information to the network device, wherein the first capability indication information is used for indicating that the first device supports a relay service. <EOS>