A memory management method, a memory storage device and a memory controlling circuit unit are provided. The method comprises: obtaining an erased state voltage of a first memory cell and a programmed state voltage of the first memory cell, where the first memory cell is operated in a first programming mode; and operating the first memory cell in a second programming mode if a width of a gap between the erased state voltage and the programmed state voltage is larger than a first threshold value. Accordingly, the reliability of the first memory cell may be improved.