1. A method for automatically creating a fill-file, for a memory storage device coupled to a host system, wherein the memory storage device comprises a memory chip, and the memory chip has a plurality of physical blocks, the method comprising: grouping the plurality of physical blocks into at least a data area, a spare area, and a system area; configuring a plurality of logical addresses and grouping the plurality of logical addresses into a plurality of logical blocks to be mapped to the physical blocks in the data area; when the host system is powered on, if the plurality of logical addresses have been formatted into at least one partition by using a file system and said at least one partition comprises a partition boot record (PBR), a file allocation table (FAT), and a root directory, reading the PBR and the root directory to determine whether a fill-file of a predetermined file capacity exists in the memory chip; if the fill-file does not exist, when the host system is about to read the FAT, configuring a sector amount corresponding to the predetermined file capacity, defining a plurality of specific sectors conforming to the sector amount by starting from a predetermined sector of the FAT, filling a plurality of cluster entry values related to the fill-file into the plurality of specific sectors, and transmitting the FAT to the host system after setting the logical addresses corresponding to the plurality of specific sectors to a write-protect status; and when the host system is about to read the root directory, filling a fill-file header of the fill-file into the predetermined sector of the root directory, and transmitting the root directory to the host system after setting the logical address corresponding to the predetermined sector of the root directory to the write-protect status.