The present invention provides a data storage device including a flash memory, a plurality of counting control arrays and a controller. The flash memory includes a plurality of chips, each chip has a plurality of pages arranged to be assembled into a super block according to a predetermined order, and each of the super blocks includes the pages of the different chips. The controller keeps the value of a first field of a first counting control array corresponding to a first chip required to be read and writes a second value into the other fields except for the first field of the first counting control array when the first field is a first value, and writes the first value into the first field and keeps the values of the other fields of the first counting control array when the first field is the second value.