The present disclosure discloses a method and an apparatus for managing quality of service in a wireless communications system. A radio access network device receives service data through n bearers between a core network device and the radio access network device, where the service data includes a plurality of service flows mapped to the n bearers, and n is an integer greater than or equal to 1. The radio access network device performs flow demapping of the received service data according to a QoS rule, to obtain the plurality of service flows. The radio access network device maps, according to the QoS rule, at least some of the plurality of service flows obtained through the flow demapping to t bearers between the radio access network device and a user equipment for transmission, where t is an integer greater than or equal to 1.