A database storage system based on optical disk includes a database management system installed on a server, a magnetic disk storage device and an optical disk storage device connecting, via a data connection, to the server. The database management system processes database management and data management in response to data requests and a database is created in the magnetic disk storage device, and includes a field structure generation module, a record index generation module, a storage space allocation module, a storage space status module, a record linkage module, a record split module and a database creation on optical disk module. The integrity of data is maintained during a database backup process. The optical disk containing a subdatabase accepts the management of the database management system to serve as a normal data source. The databases are hierarchically stored using the storage devices. The methods for database backup and restoration are provided.