A highly efficient data characteristic identification method for flash memory is provided, including the steps of: (a) based on the LBA corresponding to the write request to the flash memory, finding K corresponding counters in the hash table through K hash functions; (b) determining whether to perform decay period computation on hash table; if so, proceeding to step (c); otherwise, proceeding to step (d); (c) performing decay period computation on the hash table; (d) performing state update computation on the hash table; and (e) checking the hash table state and determining whether the data in the logic block corresponding to the flash memory is frequently updated. The method contains the decay period computation, state update computation, and checking on the data in the corresponding counters in the hash table to determine whether the data is frequently updated. Therefore, the object of a highly efficient data access characteristic identification method for flash memory is provided.