A service bandwidth configuring method of is provided by this invention, which includes the following steps: defining various kinds of service classes according to the characteristics of various services provided by a network system; defining various kinds of bandwidth specifications of the network system; establishing the mapping relationships between the various kinds of service classes and various kinds of bandwidth specifications; and configuring the service bandwidth of the network system with the mapping relationships. Besides, this invention also provides a network management system. This invention is intended to be applied to the interfaces between NMS and EMS, or interfaces between EMS and NE, and it facilitates the intercommunication between the network management systems of different manufacturers, and the unified management on network management system or devices from different manufacturers by the upper layer network management system.