A three-dimensional memory device, such as 3D AND Flash memory device, includes a first page buffer, a second page buffer, a sense amplifier, a first path selector, and a second path selector. The first page buffer and the second page buffer are respectively configured to temporarily store a first write-in data and a second write-in data. The first path selector couples the sense amplifier or the first page buffer to a first global bit line according to a first control signal. The second path selector couples the sense amplifier or the second page buffer to a second global bit line according to a second control signal.