This specification discloses a method of managing data snapshot images in a storage system. The method includes the steps of: establishing a section allocation system that includes at least a media extent; establishing a section allocation table and a block association set in the media extent, wherein the section allocation table has a field containing information pointing to the block association set and the block association set corresponds to a Source Volume as the basis for performing a snapshot backup thereof; establishing a block association table in the block association set, wherein the block association table is used to store cross-reference information in order to correspond to backup data with the original storage addresses; and copying the data before updating the data into the section association set, when the data in the Source-Volume need to be updated.