The Z-pinch driven fusion-fission hybrid reactor (Z-FFR) concept, proposed by CAEP, utilizes high-energy neutrons produced by Z-pinch driven inertial confinement fusion (ICF) to drive the sub-critical fission reactor for energy release. The Z-FFR innovative concepts such as local-holistic-ignition fusion target and advanced sub-critical power reactor, and it has advantages in security, economy and environment, and might promisingly be a millennial energy source which could effectively solve the climate problem and deal with the energy crisis. This paper introduces the current status of the conceptual research on Z-FFR in CAEP. The principle, structure and operation characteristics of the energy system are expounded in three aspects, the fusion-target design, the low-repetitive Z-pinch driver and the sub-critical fission reactor. The costs of the system are estimated, and the future developmental roadmap is put forward.