A data storage device including a flash memory, a temperature sensor, and a controller. The temperature sensor detects surrounding ambient temperature. The controller reads the temperature sensor to obtain a current temperature parameter at a predetermined time, compares a plurality of write temperatures of the blocks with the current temperature parameter one by one, and writes data stored in at least one first block of the blocks into at least one third block of the blocks, wherein the first block corresponds to at least one first write temperature of the write temperatures, and the difference between the first write temperature and the current temperature parameter is greater than a predetermined value.