A data structure for an image file includes an image file head, a data area, an index table, and file tail information. The image file head records hardware parameter information of a storage device and partitions the storage device into a plurality of data units. The data units are compressed to generate corresponding compressed data blocks. The generated compressed data blocks are stored in the data area. The index table uses an index value to record start positions of the data units and positions of the compressed data blocks in the image file into the index table. The file tail information marks a file length of the image file. During network transmission of the image file, a destination may restore the received compressed data blocks to the corresponding positions.