A data reading method adapted to a rewritable non-volatility memory module having physical blocks is provided, wherein each physical block has a plurality of physical pages. In the data reading method, each physical page is partitioned into bit data areas, where at least one of the bit data areas has a data length different from that of the other bit data areas. Data is written into the bit data areas. Data in each bit data area is corresponding to an ECC frame. The data is read from the bit data areas. Because the at least one of bit data areas has a relatively short data length, the error correction capability is improved and the data can be correctly read. An error bit information is obtained according to the read data. A log likelihood ratio (LLR) lookup table or a threshold voltage is adjusted according to the error bit information.