The embodiment of the invention provides a sensing circuit, a memory device and a method for operating the memory device. The sensing circuit comprises a power input end, an input node, a sensing node, an output node, a pre-charging circuit, a partition unit and an output unit, wherein the input node, the sensing node and the output node are sequentially connected; the pre-charging circuit is coupled between the power input end and the sensing node; the partition unit is coupled between the sensing node and the input node; the output unit is coupled to the sensing node and is configured to output a first output signal at the output node according to the voltage of the sensing node; when the voltage of the sensing node is smaller than a set threshold level, the first output signal is in a first logic level; when the voltage of the sensing node is greater than or equal to the set threshold level, the first output signal is in a second logic level; the partition unit responds to the first output signal to cut off the first logic level; and the partition unit responds to the first output signal to turn on the second logic level.