A method of generating an image file may generate corresponding image files from data units in a first storage device of a source. The method of generating an image file includes generating an image file head according to hardware parameter information of the first storage device; partitioning the first storage device into a plurality of data units with the same size; performing a compression process to compress data in the data units, respectively, thereby generating corresponding compressed data blocks; sequentially storing the compressed data blocks in a data area of the image file; creating an index table to use an index value to record start positions of the data units in the first storage device and positions of the compressed data blocks in the data area into the index table; and creating a file foot information to mark a file length of the image file.