An object of the present invention is to provide a management method of network device, which can implement concentrate management of a large number of network devices with a small amount of IP resources, and thereby reducing maintenance workload and facilitating network management. In the management method of network devices according to the present invention, the plurality of network devices compose a cluster, wherein at least one network device is designated as the cluster management device and is configured with a public IP address; other network devices are configured and updated with private IP addresses and routes by said cluster management device; the network management device manages the network devices in the cluster through the following steps: (A) establishing IP data channels via said cluster management device between the network devices in the cluster and said network management device by said cluster management device; and (B) managing the network devices in the cluster through said IP data channels by said network management device.