A method for managing blocks in a flash memory is provided, which includes dynamic and static block managing methods. In the dynamic block managing method, a blank block is selected as a swap block for write operation. During each write operation, new data and/or original data in an object block to be operated are written into the swap block, and the object block is erased. Then, a logical address of the object block is changed to be a logical address of the swap block, so that the object block served as the swap block for a next write operation. In the static block managing method, a variable seed parameter is set. Different values of the seed parameter are each associated with a logical address of a respective flash memory block. When the value of the seed parameter varies, data in the flash memory block and the swap block associated to the value of the seed parameter are exchanged, so that the flash memory block associated to the value of the seed parameter becomes the swap block for the next write operation.