A method and device for configuring a data flow are disclosed in embodiments of this disclosure. The method includes: transmitting indication information to an SDAP entity receiving end if a DRB corresponding to a QoS data flow is changed from a source DRB to a target DRB. The indication information is used to indicate that transmission of a first QoS data flow is completed on the source DRB or transmission of data of a second QoS data flow starts on the target DRB. Data of the QoS data flow includes data of the first QoS data flow and data of the second QoS data flow.