A data storage device including a flash memory and a controller. The controller enables the flash memory to transmit a predetermined parameter stored in the flash memory according to a first predetermined trigger edge of a clock signal and reads the predetermined parameter transmitted by the flash memory according to the first predetermined trigger edge of the clock signal to obtain a first reference parameter in an asynchronous mode. The controller enables the flash memory to switch to a synchronous mode and transmit the predetermined parameter and reads the predetermined parameter transmitted by the flash memory according to the first predetermined trigger edge of the clock signal to obtain a second reference parameter in a detection mode.