Abstract: The high efficiency supercritical carbon dioxide power generation system and the method therefor according to the present invention comprises: a hydrogen separation unit for receiving a gaseous fuel and separating the same into carbon monoxide and hydrogen; a combustion processing unit for receiving carbon monoxide and non-condensing gas discharged from the hydrogen separation unit to generate combustion gas; a carbon dioxide high purity unit for separating carbon dioxide from the combustion gas discharged from the combustion processing unit; a compression unit for pressurizing the carbon dioxide discharged from the carbon dioxide high purity unit; and a turbine unit for receiving the pressurized carbon dioxide from the compression unit to generate electricity, wherein the carbon dioxide discharged from the turbine unit may be supplied to the combustion processing unit again.