The embodiment of the invention discloses a flux charging method, system and device. The method comprises: control function network element of IP multimedia sub system IMS network receives flux information from service strategy decision-making function; the control function network element acquires flux charging according to flux information and outputs flux charging ticket. Flux charging of IMS-ALG mode serves as a supplementary charging mode under PCC structure and an effective charging mode when SIP network is in IMS-ALG mode.