A refreshing method suitable for a memory device is provided which includes the following steps. A sleep mode is set and the memory device cannot be read and programmed in the sleep mode. A first and a second memory cell arrays are sequentially auto-refreshed, and the steps for auto-refreshing each of the first and the second memory cell arrays individually include: during an equalization period, switching the potential of a sense line pair, a first bit line pair and a second bit line pair to a reference voltage wherein the sense line pair is not coupled to the second bit line pair, and during a refreshing period, adjusting the potential of the first and the second bit line pairs according to a refresh sequence of the first and the second memory cell arrays, thereby coupling the sense line pair to one of the first and the second bit line pairs.