The invention discloses a network management system, which has a fixed main program version consisting of a server charging program and a workstation charging system. Functions are expanded by customizing a plug-in unit of the server charging program and the plug-in unit of the workstation charging program and the data interaction with a third part program is carried out through the plug-in units. When the network management charging system is required to be combined with the third part program, the plug-in unit which is adopted in interface implementation and used for carrying out a data exchange by a form agreed with the third part program is simply arranged and a main program is not required to be reinstalled; all the individual requirements can be met with only one version of both the server charging main program and the client charging main program maintained, so the use is convenient.