A data storage device includes a memory device and a memory controller. The memory controller selects a predetermined memory block to receive data and accordingly records multiple logical addresses in a first mapping table. When the predetermined memory block is full, the memory controller edits a second mapping table or a third mapping table based on the first mapping table. The memory controller determines whether the first mapping table has recorded logical addresses of a predetermined number of consecutive logical pages. If not, the memory controller edits the second mapping table. If so, the memory controller skips editing the second mapping table and edits the third mapping table instead, so as to record the mapping information of a predetermined logical page among the predetermined number of consecutive logical pages as representative mapping information in a corresponding field of the third mapping table.