Example transmission rate control methods and apparatus are described. One example method includes obtaining a user equipment aggregate maximum bit rate (UE-AMBR) by a master base station. The master base station determines, based on the UE-AMBR, a first UE-AMBR used for the master base station and a second UE-AMBR used for a secondary base station. The master base station sends the second UE-AMBR to the secondary base station, and sends instruction information used to instruct the secondary base station to control data splitting for the master base station to the secondary base station. In this application, a transmission rate between each base station and a UE is controlled by allocating a UE-AMBR.