A region descriptor management method and an electronic apparatus are provided. The region descriptor management method is adapted to a device controller of the electronic apparatus and includes following steps. Region descriptor entries are fetched from a region descriptor table. Each of the region descriptor entries includes a block initial address and a block length to describe a memory block of a memory module. According to the block initial addresses and the block lengths of the region descriptor entries, a portion of the region descriptor entries are adjusted to be at least one current region descriptor entry. Based on the at least one current region descriptor entry, a current region descriptor table is generated.