The technology of this application relates to a method including, when a user equipment (UE) determines that a preset condition is met, the UE sends a session release request message or a session modification request message to a network device. The session release request message is used to request to release a first PDU session, the session modification request message is used to request to release a first quality of service (QoS) flow, and the first PDU session is one of existing PDU sessions in the UE. The preset condition includes at least one of: a quantity of existing PDU sessions in the UE reaching a first threshold; a quantity of data radio bearers (DRB)s associated with the existing PDU session in the UE reaching a second threshold; and a quantity of quality of service flows associated with the existing PDU session in the UE reaching a third threshold.