1. A method for accessing a flash memory module, wherein the flash memory module comprises a plurality of data blocks, and the method comprises the steps of:
receiving data from a host device;
determining if the data received from the host device is cold data or hot data;
if the data is determined as the cold data, using a two-bit-per-cell mode or a three-bit-per-cell mode to write the data into one of the plurality of data blocks; and
if the data is determined as the hot data, using a one-bit-per-cell mode to write the data into another one of the plurality of data blocks.