Apparatus and method for data synchronizing of energy management system

Disclosed are an energy management system and a data synchronization method thereof. The energy management system and the synchronization method thereof comprise: determining a synchronization target server for downloading synchronization data; and downloading the synchronization data from the determined synchronization target server. And, the energy management system determines whether the operation state of a client device is capable of synchronization based on the downloaded synchronization data, and performs the synchronization operation of the downloaded synchronization data based on a determination result.