The present invention disclosures a phase change memory unit, wherein comprising from bottom to top: a bottom electrode, a heating electrode, a phase change unit and a top electrode, the phase change unit is a longitudinally arranged column, which comprises: a cylindrical selector layer, a circular barrier layer and a circular phase change material layer form inside to outside; wherein, the bottom electrode, the heating electrode and the circular phase change material layer are sequentially connected, and the selector layer is connected to the top electrode. The present invention using trench sidewall deposition or via filling, forming the cylindrical phase change unit which is a circular nested structure, which can improve reliability of a device, greatly reduce volume of a phase change operation area and heat energy required, thus heating efficiency is improved obviously, the power consumption of the device is reduced, and high-density storage is realized.