A data storage device includes a memory device and a controller. The memory device includes at least an MLC block. The MLC block includes a plurality of physical pages. The controller is coupled to the memory device. When the controller determines that a sudden power-off has occurred during a previous write operation for writing data onto the MLC block, the controller finds a predetermined page that has been attacked by the sudden power-off, double programs the predetermined page and a first page that is directly related to the predetermined page and dummy programs a plurality of second pages that are indirectly related to the predetermined page.