The present disclosure relates to a communication technique for converging a 5G communication system for supporting a higher data rate after a 4G system with IoT technology. The present disclosure can be applied to intelligent services based on 5G communication technology and IoT-related technology. According to an embodiment, a method for providing a MA PDU service to a UE by a UPF device in a mobile communication system may include receiving an N4 rule including a traffic transmission method for downlinks (DLs) to the UE from an SMF device, wherein the DLs include a DL of 3GPP access and a DL of non-3GPP access; receiving a split ratio change report for UL traffic to the 3GPP access and UL traffic to the non-3GPP access from the UE; generating a traffic counter based on the received split ratio change report; and transmitting the split ratio change report to the SMF device.