The present invention provides a flash card and a method for flash memory to prevent data from being damaged. Firstly, when a controller completes to write data in a plurality of pagings of a first block of the flash memory, a final weak paging of the a plurality of pagings is found. Then, a first strong paging corresponding with the final weak paging is found. Then, a plurality of strong pagingsbetween the first strong paging and the final weak paging are determined. Finally, the data of the a plurality of strong pagings are copied to a backup data storage region of the flash to recover thedata when the data are damaged.