Abstract: If the operation can not be interrupted in a system, the hot backup would be a effective backup method.To the traditional hot backup system, the backup document is large and it is difficult to transport it to other computer through the network.In order to improve it, the author implemented an incremental hot backup system.When a block of data is changes, the information of the location and the content of the amending point would be written in a backup file, then the backup file can be transported through the network.When it is necessary to restore data, based on the results of the cold, the data would be restored correctly using the backup files.Thus the backup would be performed safely without interrupting the operation of the system.