A defragmentation method includes the steps of: a) configuring a processor to determine a type of a target machine-readable storage device coupled electrically to the processor; b) configuring the processor to select, from among a plurality of pre-established defragmentation algorithms respectively for performing defragmentation on different types of machine-readable storage devices, a defragmentation algorithm that corresponds to the type of the target machine-readable storage device as determined in step a); and c) configuring the processor to perform defragmentation on the target machine-readable storage device according to the defragmentation algorithm as selected in step b).