The invention relates to an incremental synthetic backup method and device for an SQL Server database, a computer device and a computer-readable storage medium, wherein the method comprises the following steps: if the database to be backed up is not the first backup, the change amount between the database to be backed up and the database to be backed up and the database to be backed up most recently is calculated; If the change amount exceeds the reserve amount threshold, the database to be backed up is backed up completely; If the amount of change does not exceed the spare capacity threshold,incremental backups are performed on the database currently to be backed up. The incremental composite backup method for SQL Server databases described above, By comparing the backup thresholds, a suitable backup method is selected between incremental backup and full backup, which avoids the situation that the differential backup time window exceeds full backup, and effectively increases the efficiency of incremental synthetic backup for SQL Server database.