A novel 3D RRAM concept using a stackable multi-layer 1TXR memory cell structure is proposed. The access transistor is fabricated in silicon, which has excellent affinity to the standard CMOS process. Using an 8-layer metal of stacked 1TXR (X=64) as an example, the density is over 260% higher than that of the conventional single layer 1T1R structure. Further, a corresponding operation algorithm is put forward, which can inhibit effectively mis-write and mis-read caused by sneaking current and reduce power consumption.