Embodiments of the present invention disclose a method for managing network device data and a network management system. The method including: storing identifiers respectively for different types of device data at the device side; the network management system storing the identifiers of the different types of device data into a database of the network management system upon synchronizing the device data; and during TRAP message processing and timing data synchronization, the network management system comparing the identifiers locally stored with the identifiers from the device side, and performing a corresponding update according to the comparison result.