Method and system for setting up a bearer are disclosed. The bearer setup method includes these steps: a packet data network gateway (PGW) obtains first quality of service (QoS) information and a first bearer identifier (ID), and sets up a bearer between the PGW and a radio access network (RAN) according to the first QoS information, where the bearer is associated with the first bearer ID; the RAN sets up a radio bearer (RB) with a user equipment (UE) according to second QoS information associated with the first QoS information, where the RB is associated with a second bearer ID associated with the first bearer ID.