A data processing method for a memory storage apparatus having physical blocks is provided. The method includes: grouping the physical blocks into a data area, a spare area and a system area; configuring a plurality of logical addresses which would be formatted into a file allocation table area having cluster entry fields, a root directory area having directory entry fields and a file area having clusters; storing a communication file from the Kth cluster of the file area; recording a file description block corresponding to the communication file in the Mth directory entry field and storing an end of cluster chain mark in the cluster entry field corresponding to the last cluster of the clusters where the communication file stores, and K and M are positive integers which are larger than one. Accordingly, the method can prevent the communication file from being overwritten after the memory storage apparatus is formatted.