A data storage device includes a memory device and a memory controller. The memory controller selects a predetermined memory device to receive data and accordingly records multiple logical addresses in a first mapping table. The first mapping table records which logical page the data stored in each physical page of the predetermined memory block is directed to. When the predetermined memory block is full, the memory controller edits a second mapping table and a third mapping table according to the first mapping table. The second mapping table corresponds to multiple logical pages and records which memory block and which physical page is the data of each logical page stored in. The third mapping table corresponds to the physical pages of the predetermined memory block and indicates whether each physical page is a valid page or an invalid page.