An innovative high-efficiency power generation system is developed and investigated in this paper. Based on self-sustaining supercritical water coal gasification, the thermal energy of the syngas is cascade utilized according to its temperature and pressure, both sensible and latent heat of the syngas can be recycled into the system, and thereby the net power efficiency can be about five percentage points higher than that of the traditional GE gasification based power plant. The exergy analysis shows that the exergy efficiency of the proposed system reaches 49.17%, which is 10.72% higher than that of the reference system, and the improvement in exergy efficiency of the proposed system mainly comes from the exergy destruction decline of the syngas energy recovery process and the gas compression process. The syngas combustion process is the highest exergy destruction process with a value of 183.77 MW in the proposed system. Further improvement in the system performance of the proposed system lies in the utilization of syngas.