This paper presents a unique design of a total-flow geothermal power generator that uses Turgo turbine and two-phase supersonic nozzles. The high-speed flashing jets are formed by high-pressure subcooled liquid from the well through the nozzles and impinge turbine blades obliquely to drive the Turgo turbine. This new generator converts geothermal power directly from the geothermal fluid without implementing any phase separator or heat exchanger, which results in a simple and easy-to-maintain system. A prototype of the total-flow geothermal power generator was built and field-tested in Yilan, Taiwan. Results show that compared to traditional Organic Rankine Cycle generators and double flash geothermal power plants, the new design has a competitive geothermal efficiency operating at moderate reservoir enthalpies.