A data storage device including a flash memory, a temperature sensor and a controller. The flash memory has a plurality of blocks, and each of the blocks has a plurality of pages. The temperature sensor detects surrounding ambient temperature and to produce a temperature parameter accordingly. The controller is arranged to perform a first maintenance procedure after a predetermined period since the data storage device is powered on. The controller reads the temperature sensor to obtain a first temperature parameter in the first maintenance procedure and determines a first time span according to a first predetermined condition for performing a second maintenance procedure, wherein the first predetermined condition includes the first temperature parameter, and the controller is further arranged to perform the second maintenance procedure after the first time span since the first maintenance procedure has finished.