The present invention provides a data storage device including a flash memory and a controller. The flash memory includes a plurality of blocks. Each of the blocks has a plurality of pages. The flash memory stores data of a plurality of logical addresses. The controller reads a first current block and a second current block from the flash memory in sequence to build a first current block table and a second current block table and builds a bit table according to the logical addresses of the pages of the second current block when the data storage device is resumed from a power-off state, wherein the controller further organizes the first current block table and the second current block table according to the bit table.