The present invention provides a method for accessing a flash memory module, wherein the method includes: building a physical address to logical address (P2L) table; receiving a read command asking for a data within the flash memory module, wherein the read command includes a first logical address; if the P2L table does not include information associated with the first logical address, reading a logical address to physical address (L2P) table from the flash memory module, and searching a first physical address corresponding to the first logical address according to the L2P table, wherein the first physical address is used to read the data from the flash memory module; and using the P2L table to update the L2P table.