The invention discloses a memory device and a forming method thereof. According to the technical scheme of the embodiment of the invention, most of carbon nanotubes in a carbon nanotube stacking structure in a memory cell are enabled to be stacked in a basically consistent manner, so that the setting/resetting voltage or current of the memory device is controlled, and the performance of the memorydevice is improved. Meanwhile, the forming method provided by the embodiment of the invention is compatible with the existing semiconductor process and is easy to implement.