Embodiments of the present invention provide a method, an apparatus, and a system for QoS control based on a charging system. In solutions provided by the embodiments of the present invention, after a service resource reservation request from a PCEF is received, a preset QoS value for a service may be directly determined according to a service identifier of the service from a locally stored mapping relationship between service identifiers and preset QoS values of services, and a QoS value for the service is determined according to the preset QoS value, and the determined QoS value is directly delivered to the PCEF, so that the QoS value for the service may be determined and delivered without the participation of the PCRF, so as to significantly reduce the time for determining the QoS value for the service.