The invention provides a database cluster difference comparison and data synchronization method and system and a medium. The method comprises the steps that 1, constructing a database cluster, a nodedatabase and an adjacent node backup library; 2, grouping tables in the database, enabling each group of tables to have a foreign key connection relationship, enabling fields of the tables in the groups to depend on each other, selecting the groups which need to be compared and synchronized, and generating corresponding data tables; 3, establishing an initial backup point for the submitted data table, storing the initial backup point in a backup library and a database to serve as an initial comparison benchmark for comparison, and obtaining a data increment; 4, synchronously reporting the database, and when the reported data is sent to the sender node, comparing the management website and verifying the synchronous data, and then selecting agreement or rejection; and 5, maintaining the database, including business data maintenance, dictionary data maintenance, data backup and restoration and log management.