A method for managing data stored in a flash memory is provided, where the flash memory includes a plurality of blocks. The method includes: providing a program list, where the program list records information about programmed blocks of the plurality of blocks and sequence of write times of the programmed blocks; detecting quality of a first block of the plurality of blocks to generate a detecting result, where the first block is the programmed block that has an earliest write time; and determining whether to move contents of the first block to a blank block, and to delete the contents of the first block according to the detecting result.