A data access method for accessing a non-volatile memory module is provided. The data access method includes configuring a plurality of logical addresses and grouping the logical addresses into logical blocks to map to the physical blocks of the non-volatile memory module, and a host system formats the logical addresses into one partition by using a file system and the partition stores at least one file and a file description block corresponding to the file. The data access method further includes searching an end mark corresponding to entry values of the file description block, setting logical addresses storing the end mark as default pattern addresses, and setting values stored in the logical addresses as default values corresponding to the default pattern addresses. Accordingly, the data access method can divide one partition into a write protect area and a writable area by updating data stored in the default pattern addresses.