An exemplary method for reading data stored in a flash memory. The method comprises: controlling the flash memory to perform a first read operation upon the memory cell with a first threshold voltage to obtain a first binary digit for representing a bit of the N bits data; performing an error correction hard decode according to the first binary digit; controlling the flash memory to perform a second read operation upon the memory cell with a second threshold voltage to obtain a second binary digit for representing the bit of the N bits data, if the error correction hard decode indicates an uncorrectable result; and performing an error correction soft decode according to the first binary digit and the second binary digit.